Butachlor (N-(butoxymethyl)-2-chloro-N-2, 6-diethylacetanillide) is widely used chloroacetanilide herbicide in Asian region, especially in the north of Iran. Several studies have been reported on toxicity of butachlor, but little information is accessible on DNA damaging potential. Thus, the present study was undertaken to investigate of DNA damage by butachlor in Cyprinuscarpio(Pisces: Cyprinidae) using single cell gel electrophoresis. This study was done according to static method. The specimens were exposed to different concentrations of butachlor (0.07, 0.15 and 0.3 mgl-1) and sampling was carried out after 48 hour (short-time exposed). Based on the results, a significant increase in genetic damage index was observed in treatments compared with control samples (P<0.01). Also, the results showed the genotoxicity potential of this herbicide on fish. This study corroborated that comet assay is applied on the fish is a functional method to determine potential genotoxicity pollutants.