The Kura and Aras rivers are largest rivers of the Caucasus rising from Turkey flowing through the Georgia, Armenia, Azerbaijan and Iran, draining to Caspian Sea. This study was carried out at 20 sampling sites along the entire basin between the years 2014 and 2015 in order to describe the diversity of the ichthyofauna of the Kura-Aras River Basin. Fish were collected with the use of an electrofishing device in streams and gill nets in lakes. A total of 19 fish species were observed in the study period. Based on previous studies and the sampled species during the study period, we document the presence of 32 fish species belonging to 11 families living in the Turkish part of the basin. Of these, 23 fish species are endemic to the Kura-Aras River and Caspian Sea basins, and are not found in any other river basins of Turkey.