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Quarantine Flag

Last modified: 2020-03-22 by rob raeside
Keywords: international code of signals: q | international code of signals: quebec | quarantine flag |
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[Signal Letter Q]
by António Martins-Tuválkin

See also:

Bandiera della sanitaria

The documents of 1580 from Split mention requirement of the sanitary services to carry "bandiera della sanitaria" on ships depending on their destination.

This is probably connected with plagues and would presumably mean that the ship was sanitary inspected before leaving the port.

I guess that similar provision were usual elsewhere in Europe at the time (and afterwards, even until today!) however, when was this practice established and how the flag was looking like? How it was used?

I seems to remember that "quarantine flag" is supposed to be yellow - is this the same thing and was the yellow flag usual in 16th century already?
Željko Heimer, 23 November 2006

Flag Quebec, plain yellow, is known as one of the oldest flags among the International Signal Code flags, but 1580 seems to me to be a bit too far back. The modern meaning is also that the ship flying it, requests free pratique and the flag declares the ship to be healthy. I have read somewhere, however, (unfortunately the original source escapes me) that plague ships were required to hoist a black flag to indicate that they have the disease onboard and are therefore under quarantine.
Andries Burgers, 23 November 2006

The Quarantine Flag

1. History of the quarantine flag

[This should probably be placed a "generic" page on the FOTW website on quarantine flags, which would include an index of the specific quarantine pages found on the FOTW website. The "Quarantine Flags" page, should be renamed more specifically. This section should also be dispatched among the editors of the French, German, British, Danish, and Swedish sections of the wesbite.]

The history of the quarantine flag was related by Bernard Dulou in Rose des Vents #106, 2004. Rose des Vents is the bulletin of the association ABB (Association Bateaux en Bouteille).

The yellow quarantine flag is universal (Q letter in the international signal alphabet). Following the establishment of quarantine in the Mediterranean ports in the 14th century, it seems that there was for centuries no proper quarantine flag or any other quarantine signal.

The first time and place of hoisting of a quarantine flag is hitherto unknown. This gap was highlighted in 1975 by Rupp, who was the first in the German naval literature to write on the quarantine flag. The oldest known information on the use of signal flags to indicate quarantine dates back to the 18th century. At the time, signals were also used to indicate the absence of contagious disease on board. The oldes known record is to be credited to Henningen, who writes: "Danish sources give information according to which, during the great plague of 1710-1711, ships placed in quarantine should hoist a white flag." Hennigen adds that the quarantine signal should be used as the jack when the ship was in quarantine, as it was the case in 1751 in Cadix for the Swedish "Prins Carl" on her way to the East Indies. However, this flag was also hoisted as the jack to indicate that there was no contagious disease on board, as it was the case in 1799 in Capetown for the Swedish "Kongen af Danmark" on her way to China. It seems also that the Danish corvette Galathee hoisted in 1846 in Hawaii harbour a white flag in order to indicate that the health situation was normal on board. The very same white flag was then used with two opposite meanings, either quarantine or absence of disease on board.

An extract of the health report of the port of Marseilles (Health Office), dated 1730, describes the quarantine rules with details comparable to modern practice: everything is written, every member of the health service has its duty well defined, but there is no mention of a quarantine flag.

All the ships were controlled on the port of the island of Pommègue, located five miles off Marseilles, where 35 ships could moor. The contaminated ships were sent to the islands of Frioul and Galiane. All the other ships were allowed to enter the port of Marseilles, provided they moored again near the St. Nicolas citadel for checking their bill of health. The small boats plying between the port and the suspect or quarantined ships flew a red pennant.

In Britain, the quarantine signals were introduced in the 18th century. Mullet writes that, as from 1 January 1789, every quarantined ship off the British coast should hoist a specific signal. The daily signal was a big yellow flag whereas the night signal was a light placed on top of the mainmast. The non-observance of the rule was fined 200 pounds.

According to Fergusson, the origin of the yellow flag has to be traced back to the Middle Ages, when the heretics had to wear yellow clothes, the yellow colour being considered as the symbol of the hell fire, of betrayal, of jealousy and treachery. This was indeed a negative colour. The meaning of the "Yellow Admiral", known in the 19th century, is probably related. A "Yellow Admiral" was an old or supernumerary Captain who, short before retirement, was appointed Rear Admiral without ever having hoisted their personal flag on a ship of either the red, yellow or blue squadron. The name of "Yellow jack" given by the British seamen to the yellow fever seems to be related, too. During the great plague epidemics, it was common to mark the houses of the infected houses with a yellow cross and to force their inhabitants to wear yellow clothes.

An English Decree dated 1799 prescribes the size of the quarantine flag as "six breadths of bunting", which means six times the size of an ordinary flag. The "London Gazette" from 6 April 1805 published a Decree prescribing in detail the quarantine moorage, limited by yellow buoys topped with a yellow flag. The Decree from 10 October 1806, however, prescribed an "eight breadths of bunting yellow and black flag".

In 1832, the Nautical Magazine published a Decree, similarly prescribing a flag with yellow and black squares, eight breadths of bunting in size, to be hoisted by the quarantined ships on the coasts of Britain. The signal had to be hoisted on top of the mainmast. The naive lacking the bill of health has to fly on day a big yellow flag with a black ring or a plain black disc in the middle. This flag was tow breadths of bunting in size.

In Germany, the oldest record of the use of a quarantine flag is found in a report by Janssen, the Chief Pilot of the port of Hamburg. For long, there was no choice between the green and pale yellow colours for the flag. It was claimed that those two monocolour flag would prevent confusion with any national ensign. Therefore, the green flag was used for long in Hamburg as the quarantine flag. In 1856, a Decree lists also toe yellow flag: "All the ships submitted to a quarantine inspection are allowed to sail up the river Elbe and to moor under the quarantine flag. The flag is a green flag, two ells in size, hoisted on the foremast. The ships not having such a flag shall used a yellow flag or the national ensign."

In the Health Inspection Decree of the ships of the port of Hamburg issued in 1883, only the yellow flag is prescribed. The international use therefore eventually prevailed. Denmark adopted the international use in 1887 by a Notice published on 20 June, recommending the use of a yellow flag to the Danish ships.

Today, the Q signal flag is included in the international signal code. Hoisted alone, it means: "My ship is healthy and I require the free practice." Indeed, it is mostly used to require the inspection by the customs authorities, but that use is not strictly the same everywhere. In Britain, every ship coming from abroad must hoist the Q flag on the port side and wait for the Customs, who are also in charge of immigration and health control. In theory, the crew shall not be allowed to land before the completion of the inspection. The procedure is simpler in France, where only the ships transporting goods to be declared have to hoist the Q flag.

An illustration of the yellow flag can be seen on the painting "HMS Hazard flying yellow quarantine flag", by Sir Oswald Walter Brierly (1817-1894, painting made 20 September 1841), kept in the National Maritime Museum, London.

2. Origin of the word "quarantine"

The website of the Australian Quarantine and Inspection Service explains the origin of the word "quarantine" as follows: "The word quarantine comes from the Italian quaranti giorni, meaning '40 days'. When bubonic plague swept through Europe in the 14th century, the government of Venice required ships to anchor away from the city for 40 days before they could unload passengers or cargo. The authorities thought 40 days would be enough time for any disease to be identified and either treated or pass through its normal course. All ships under quarantine had to fly a yellow flag."

Ivan Sache, 26 November 2006



As I already suggested the ports in Adriatic had regulations regarding the "bandera della sanitaria" in 16th century as well established practice. The question is, for the time being how this was looking like, but that is an other issue. I hope to provide more details on the practice eventually.

I guess that this is at least suspicious and that with the research of Venetian and other Adriatic (and Mediterranean) ports' documents would reveal that quarantine flags were in use ever since the concept of the quarantine was introduced in 14th century.
Željko Heimer, 26 November 2006

Origin of the word

The article from Australian Quarantine and Inspection Service seems to imply that the yellow flag was established already in 14th century (if you read it giving some leeway), however, this needed not to be the intention of the writer - he might have just claimed that the yellow flag is traditional for this purpose nowadays as quite an old heritage, but not necessarily from Venetians.
Željko Heimer, 26 November 2006

Quarantine Laws


Quarantine Act
1908 (Act No. 3 of 1908)

21. Quarantine signals on vessels and installations

(1) The master of a vessel (other than an aircraft) subject to quarantine is guilty of an offence if he or she:

(a) fails to display the quarantine signal on the vessel before it comes within 3 nautical miles of any port or within 500 metres of an Australian installation; and

(b) fails to keep the quarantine signal displayed on the vessel while it enters, or is in, any port or quarantine station or is at an Australian installation.

Maximum penalty: 50 penalty units.


(2) The master of an installation subject to quarantine shall:

(a) display the quarantine signal on the installation; and

(b) keep the quarantine signal displayed on the installation until pratique is granted or until the installation is released from quarantine.

Maximum penalty: 50 penalty units.

23. Signal

The quarantine signal shall be as prescribed and shall be displayed in the prescribed manner.

24. Unauthorised person not to board or approach vessel or installation

(1) An unauthorised person must not:

(a) go on board or alongside any vessel subject to quarantine or on which the quarantine signal is displayed; or

(b) approach within 30 metres of any prescribed signal on a landing place.

Maximum penalty: 50 penalty units.

44. Goods not to be removed


(3) If a vessel or installation is displaying flags, lights or other signals that clearly indicate that the vessel or installation is in quarantine:

(a) any unauthorised person who lands or unships goods from the vessel or installation, or moves goods on the vessel or installation, is presumed, in the absence of evidence to the contrary, to have intended to land or unship the goods, or to have moved the goods in order to land or unship them, as the case may be; and

(b) any person who receives or has in his or her possession any goods landed or unshipped from the vessel or installation is presumed, in the absence of evidence to the contrary, to have known that the goods were landed or unshipped from the vessel or installation.

143. Saving of regulations

Any regulation prescribing a signal for the purposes of paragraph 21(1)(c) of the Quarantine Act 1908 that was in force immediately before the commencement of this Schedule continues in force as if it prescribed that signal for the purposes of subsection 21(1A) inserted by item 142.


Quarantine Regulations 2000
Statutory Rules 2000 No. 129 as amended
made under the Quarantine Act 1908

7 Quarantine signal during daylight hours (Act s 23)

8 Quarantine signal outside daylight hours (Act s 23)


Ivan Sache, 18 January 2008

Australia and New Zealand

Quarantine Regulations, from the Government Gazette, 19 January 1855:

80. The Master of any vessel detained in Quarantine shall cause a yellow flag of not less than six breadths of bunting to be hoisted at the maintopmast head, which flag shall be kept flying between the hours of sunrise and sunset, but between the hours of sunset and sunrise a lantern, shall be hoisted in the same place, and a light shall be kept burning until sunrise, under a penalty not exceeding Twenty Pounds.


Quarantine Regulations, published in each Provincial Gazette during 1864

4. The master of any vessel arriving from any port in the Australian /colonies or New Zealand which may at any time, by a notice in the New Zealand Gazette, be duly declared an infected port, and the master of every vessel arriving from any port whatsoever not within the Australian Colonies or New Zealand, shall on approaching any port in New Zealand cause the Health Officer's flag (No 8 of Marryat's code) to be hoisted at the mast or mainmast head of the said vessel, and shall keep the same flying until she has been communicated with by the Harbour Master, Pilot, or other officer of the port, after which, if the vessel be considered clean, the said flag may be hauled down. If any such vessel shall call at more than one New Zealand port, the flag herein prescribed shall be hoisted on arrival at each port.

5. Should it be considered necessary by the Harbour Master, Pilot or other officer as aforesaid that such vessel shall be visited by the Health Officer, the master shall on being directed to do so, cause the vessel to be anchored in the quarantine ground appointed for the harbour, and shall hoist the quarantine (or yellow) flag as hereinafter appointed.


8. The Health Officer shall immediately visit any vessel which has hoisted the yellow flag, and has been brought up in the quarantine ground, and if he shall find that any sickness of an infectious or contagious nature exists or shall then recently have existed on board of her, he shall declare the vessel to be in quarantine and shall submit full information in regard thereto to the Board of Health. But should he be satisfied that the sickness is not of a contagious nature he may authorise the hauling down of the yellow flag, and the removal of the vessel to the ordinary mooring ground.

9. The Master of every vessel on quarantine is to hoist at the main a yellow flag of not less than six breadths of bunting by day, and a white light by night in an ordinary globe lantern, not less than eight inches in diameter, and to keep the same respectively hoist until released from quarantine. The said lantern at the main to be in addition to the usual anchor light provided for in the Harbour regulations.


And as noted in

From the early 1870s until 1920, Matiu/Somes Island [in Wellington Harbour] was frequently used as a human quarantine station. The quarantine facility was erected on the island in 1872, shortly after the immigrant ship England came into Wellington Harbour flying the yellow quarantine flag. A monument stands on the island to those who lost their lives while confined on Matiu/Somes.

Ivan Sache, 18 January 2008


The Canadian rules for the quarantine are prescribed in Memorandum D3-5-1, issued on 11 February 1998 in Ottawa by the Canada Border Service Agency:

15. Where a vessel arrives in Canada flying a yellow quarantine flag (infectious disease), the customs inspector will not conduct normal clearance procedures until advised by the appropriate health authority that it is safe to do so. Pending such notification, the customs inspector, with the help of the local police authority or the RCMP, as deemed appropriate, will endeavour to ensure that the vessel is maintained in a sterile condition pending cancellation of the health alert by the competent health authority.

Quarantine Regulations [C.R.C., c. 1368, Section 15]

Quarantine Regulations Evidence of Immunization Maritime Traffic

15. (1) Every person in charge of a vessel who has received instructions under paragraph 13(b) shall, on approaching a port, display at the fore, as a quarantine signal, a yellow flag by day and a red light over a white light by night, in such a manner that the signal may be readily seen.   (2) No person shall remove a signal displayed pursuant to subsection (1) until the vessel has been granted clearance by a quarantine officer."


The use of the quarantine flag in Canada is ancient. Quoting Ian Cameron, "Sergey Tolstoy and The Doukhobors: The Halifax Quarantine", Canadian Medical Association Journal 174: 11 (2006): "Jan. 27, 1899 - The ship arrives in Halifax Harbour and hoists the yellow quarantine flag from its mainmast, a signal that a quarantine inspection is required."
Ivan Sache, 18 January 2008

Cocos (Keeling) Islands

The use of the quarantine flag in the Cocos (Keeling) Islands is described as follows:

Cocos Keeling Clearance Formalities

Incoming vessels must fly the Q flag and anchor in the so called inner lagoon behind Direction Island, close to the yellow quarantine buoys.

No one on board should leave the vessel nor should there be any contact with anyone until clearance is completed. Neither the quarantine buoys nor any other buoys at Direction Island are suitable for yachts, which should use their own anchors.


Ivan Sache, 7 January 2007


The use of the yellow quarantine flag in the Philippines is prescribed in Administrative Order No. 118-C (s. 1992), (aka Revised Quarantine Rules and Regulations), as follows:

A. General Sanitation Requirements for Port of Entry

1. Inspection of Vessels


d. Requirements for Vessels to be Inspected

Any vessel subject to quarantine inspection shall be considered in quarantine until given a pratique. Such vessel shall fly a yellow flag at its foremast, drop its anchor at the designated quarantine anchorage, put down its accommodation ladder, wait for the Quarantine Medical Officer and give the conveyance a proper shelter or lee in stormy weather while he is boarding and leaving the vessel. The Quarantine Medical Officer has the authority to delay quarantine inspection of a vessel until the above conditions are complied with.


3. Detention of Vessel in Quarantine


b. Requirements of Vessel in Detention

No direct contact shall be allowed between any person in the vessel in quarantine and any person from the outside. Such vessel shall fly the yellow flag while under detention in quarantine.

Ivan Sache, 7 January 2007

United States: San Diego

The use of the quarantine flag is prescribed in Ordinance no. 193 of the City of San Diego, approved on 20 February 1888 as An ordinance concerning the public health of the City of San Diego, California, as follows:


Sec. 8. Every pilot who conducts into the port of San Diego any vessel subject to quarantine, or examination by the Quarantine office, must—


Fifth—If the vessel is subject to quarantine, by reason of infection, place at the mast-head a small yellow flag.


Sec. 34. Whenever a case of small-pox, varioloid or cholera is reported to the Health Officer it shall be his duty to immediately visit the premises where the person so affected resides or may be stopping, and the said Health Officer, upon the personal inspection of himself, shall immediately cause to be erected a yellow or quarantine flag in a conspicuous place on said premises, or to post upon the doorway of houses infected with small-pox, varioloid or cholera, a placard setting forth the fact, the same to remain during the continuance of the disease on said premises.

Sec. 35. No person shall remove a yellow or quarantine flag or placard any building where the said flag or placard shall have been placed by the Health Officer, without the permission of the said Health Officer.


From The Journal of San Diego History, 48 (4), 2002

Ivan Sache, 7 January 2007


Here are the flag-related paragraphs of the Vanuatu Quarantine Act:

Quarantine Act [Cap 1]
Laws of the Republic of Vanuatu
Revised Edition 1988

Chapter 1



Quarantine Signals

7. To make herself known every vessel shall on arriving within a distance of 3 miles of the coast exhibit a yellow flag at the fore by day and a globular red light by night until such time as pratique shall have been given.

Vessels showing Quarantine signals to be considered in Quarantine

8. Every vessel exhibiting a yellow flag or a red light as described in section 7 shall be considered as in quarantine as hereinafter defined, and during such state of quarantine shall have no communication except by signal with the shore or with any boat or vessel save that of the health officer, whose boats shall when bringing a health officer on board bear a yellow flag by day and a red light by night.

Unlawful for other Boats to Exhibit Quarantine Signals

9. It shall be unlawful for any other boats to exhibit quarantine signals within the waters of Vanuatu.


Signs of Quarantine Stations and Ships

32. (1) when any place set apart and notified as a quarantine station is used as such a yellow flag shall be kept constantly flying at some conspicuous place in such station from sunrise to sunset and from sunset to sunrise shall exhibit a green light and the display of such flag or such light shall be deemed sufficient notice that such station and the land or sea surrounding it to the distance of 100 metres are in quarantine.

(2) Any vessel while in quarantine shall exhibit a yellow flag at the fore by day and a globular red light by night.


Source: Vanuatu Consolidated Legislation, from the Pacific Islands Legal Information Institute database

Ivan Sache, 26 November 2006