Dax (Dacs in Gascon) is a commune in Nouvelle-Aquitaine in south-western France, sub-prefecture of the Landes department. It is also the capital of the arrondissement of Dax and of 2 cantons in the department: Dax-1 and Dax-2.

It is well-known spa town, specialising in mud treatment for rheumatism and similar medical problems.