The present study was carried out in order to complete taxonomic survey on Iranian freshwater amphipods in East Azarbaijan, West Azarbaijan and Ardebil provinces. The results revealed that amphipods of Azarbaijan of Iran belong to family Gammaridae with two genera namely, Obesogammarus and Gammarus. Obesogammarus turcarum is restricted to the Caspian Sea drainage basin and was found along Aras River. Three species including Gammarus komareki, G. lacustris, and G. paricrenatus belong to G. pulex species group. Based on results of the present study, G. komareki was the dominant species. From zoogeographical point of view, G. komareki was found in Asia minor. Compared to the other two species, G. lacustris is distributed in the northern parts of America, Europe and Asia. Gammarus paricrenatus is endemic to Iran and in one locality was sympatrically observed with Gammarus lacustris.