national flag consisting of a green field (background) with a central crescent and star. The flag has a width-to-length ratio of 2 to 3.

Although Mauritania includes both black African and Arab-Berber populations, the official symbolism of the nation's flag and coat of arms (arms, coat of) is associated with the latter. The flag's green background and its star and crescent are traditional Muslim symbols, in use for centuries. The design is of the conservative type common before the 20th century and still used by such nations as Turkey (Turkey, flag of), the Comoros (Comoros, flag of), Tunisia (Tunisia, flag of), and the individual states of the United Arab Emirates. In many Arab countries, however, this type of design has been replaced by flags of more modern form, such as those based on the Arab Revolt Flag of 1917 and the Arab Liberation Flag of 1952, containing the four colours of traditional Arab dynasties (red, white, black, and green) in a tricolour form with either a triangle at the hoist or an emblem in the centre.

Mauritania was part of the French colonial empire until November 28, 1958, when an autonomous republic was established in order to meet rising nationalist expectations while preserving the French Community. The new national flag of the Islamic Republic of Mauritania, replacing the French Tricolor (France, flag of), was adopted on April 1, 1959. There was no change to the design when Mauritania became an independent country on November 28, 1960.