The haj, more commonly spelled hajj, is an annual Islamic pilgrimage to Mecca.

Haj or HAJ may also refer to:

• Háj (Fichtel Mountains), a mountain in the Czech Republic
• Háj (observation tower), an observation tower near Šumperk in the Czech Republic
• Háj, Košice-okolie District, a municipality and village in Slovakia
• Háj, Turčianske Teplice District, a municipality and village in Slovakia
• Hāj, other name of Hajj Qeshlaq, a village in Iran

• Haj Ross (born 1938), American linguist
• Joseph Haj, American artistic director

• The Haj (novel), a novel by Leon Uris
• Hajong language, spoken in India and Bangladesh
• HAJ, IATA code for Hannover Airport, in Germany

• Hajj (disambiguation)