The Hussein-McMahon Correspondence during World War I was a 1915-1916 exchange of letters between the Hejazi (the Hejaz later became part of Saudi Arabia) leader Hussein ibn Ali, Sharif of Mecca, and Sir Henry McMahon , British High Commissioner in Egypt, concerning the future political status of the Arab lands of the Middle East, where Britain was seeking to bring about an armed revolt against the Ottoman Empire's rule.

McMahon's second letter dated 24 October 1915 is crucial. It states that:

The districts of Mersin and Alexandretta, and portions of Syria lying to the west of the districts of Damascus, Homs, Hama and Aleppo, cannot be said to be purely Arab, and must on that account be excepted from the proposed delimitation. Subject to that modification, and without prejudice to the treaties concluded between us and certain Arab Chiefs, we accept that delimitation. As for the regions lying within the proposed frontiers, in which Great Britain is free to act without detriment to interests of her ally France, I am authorized to give you the following pledges on behalf of the Government of Great Britain, and to reply as follows to you note: That subject to the modifications stated above, Great Britain is prepared to recognize and uphold the independence of the Arabs in all the regions lying within the frontiers proposed by the Sharif of Mecca.

McMahon's promises are seen by Arab nationalists as a pledge of immediate Arab independence. They also believe that the undertaking was violated by the region's subsequent partition into British and French League of Nations mandates under the secret Sykes-Picot Agreement of May 1916.

The ambiguity that rose from the letter concerned Palestine, which was not explicity mentioned in the correspondence. The letter refers to the The districts of Mersin and Alexandretta, and portions of Syria lying to the west of the districts of Damascus, Homs, Hama and Aleppo..., but does not specifically mention the Sanjak of Jerusalem , which was Ottoman administrative division that covered most of Palestine.

Britain later promised to favour the creation of a Jewish national home in Palestine in the Balfour Declaration of November 1917. The Churchill White Paper, 1922 stated that the letter that the "districts west of Damascus" also included the Sanjak of Jerusalem and the Vilayet of Beirut (that is, Palestine).

Source of the letter: "A history of the Middle East" - Peter Mansfield. p.154, second edition