The present study was designed to evaluate the genotoxic effects of Roundup, Stomp herbicides and their combination on Nile catfish (Clarias gariepinus). The experiment was carried out on 120 fish that randomly divided into four equal groups with three replicates. The first group kept as a control, the second group exposed to 1/2 96 hrs LC₅₀ of roundup, the third group exposed to 1/2 96 hrs LC₅₀ of Stomp and the fourth one exposed to a combination of roundup and Stomp with the previously mentioned doses. The experiment was terminated at 15 days after blood samples collection and then the sera were separated for estimating 8-hydroxy 2-deoxy guanisine (8-OHdG) then the fish were sacrificed and two specimens from gills of all groups were obtained and kept at -20ºC for comet assay and the other specimens were fixed in 10% neutral –buffered formalin for histopathological examination. The results indicated that both herbicides individually cause significant increase in DNA damage that was highly obvious in the group exposed to combination of both herbicides. Histopathological investigation of gills confirmed the aforementioned findings.