Drainage of effluent from different types of industrial units poses a serious threat to the aquatic flora and fauna. Fish being an inhabitant of the closed aquatic environment, serve as a useful model for assessing the effect of chemicals mixed in the aquatic environment. In the present study, genotoxic effect of an effluent from a paper mill located at Kurukshetra was tested in Channa punctatus, a fresh water fish. The fish were exposed to the effluent for 24, 48, 72 and 96 hours. The remarkable chromosomal aberrations observed in the treated specimens included centromeric gaps, chromatid break, attenuation, acentric fragments, pycnosis, polyploidy and chromosomal gaps. The total number of aberrations was significantly higher in treated specimens as compared to controls. The results of present study clearly points genotoxic potential of the paper mill effluent on the fish chromosomes. The effluent, therefore, should be treated before discharged into the water bodies