Abstract In order to evaluate the Diptera biodiversity in the Boumerzoug sub-basin, samples were performed at five permanent oueds: El Berda Oued, Boumerzoug Oued, El Guareh Oued, Hmimime Oued, and Sigus Oued. Sampling was carried out monthly during the period from December 2014 to November 2015. The samples were taken using a Surber mesh for the lotic face with size 25 cm * 20 cm * 65 cm, 500 µm net. In total, 53484 individuals comprising 24 families were collected. The Chironomidae family is the most dominant with a population of 43553 individuals (Fc % = 81.43%), followed by the Simuliidae (5137 individuals, Fc % = 9.61%), Psychodidae (1907 individuals, Fc % = 3.57%), Ephydridae (1509 individuals (Fc % = 2.81%) and Sciaridae (313 individuals, Fc % = 0.59%). However the remained families (Culicidae, Asilliidae, Mycetophilidae, Tipulidae, Syrphidae, Tabanidae, Muscidae, Calliphoridae, Ceratopogonidae, Fanniidae, Cecidomyiidae, Anthomyiidae, Sphaeroceidae, Sciomyzidae, Stratiomyidae, and Phoridae) weree poorly represented (between 1 individual (Fc % <0.00%) to 281 individuals (Fc % = 0.53%) were collected with predominance. Finally, compared to the other families, the predominance of the Chironomidae family can be explained by the fact that this family plays an important ecological role in wetlands rich in organic matter, even clearly polluted.