Diploid chromosome number, chromosome morphologies and chromosomal band properties (with C-banding and Ag-NOR staining) of endemic Oxynoemacheilus atili Erk'akan, 2012 were revealed out from Beysehir Lake Basin, Turkey. Metaphase chromosomes were obtained from kidney cells. Diploid chromosome number was found as 2n = 50 and chromosome morphologies were as follows: five pairs of metacentric, nine pairs of submetacentric and 11 pairs of subtelo-acrocentric chromosomes. Fundamental arm number was calculated as 78. Constitutive heterochromatin regions were determined on the centromeres of chromosomes. NORs were detected on one pair of chromosomes. The obtained results may contribute to nemacheilid chromosomal studies.