Dihau is a surname. Notable people with this surname include:
Désiré Dihau (1833–1909), French bassoonist and composer, brother of Marie and Henri Marie Dihau (1843–1935), French singer, pianist, and music teacher, sister of Désiré and Henri Henri Dihau, the subject of artist Henri de Toulouse-Lautrec, brother of Marie and Désiré