The present study was carried out to evaluate the cytotoxic and genotoxic effects of the silk dyeing industry effluents on the mitotic cells of Allium cepa. A. cepa is selected for the purpose as the plants has large mono-centric chromosomes in reduced number and is accepted as suitable test material for the study of impact of the environmental toxic substances to be mutagenic. The plants were treated with the effluents at various dilutions and kept in the laboratory for 72 h with 11 sunshine hours and at room temperature at 27-30°C. There is a gradual increase in the mitotic index (MI) up to 30% dilution level and this is attributed to the fact that the chemicals present in the effluents may not interfere in the process of mitosis rather it enhances the synthesis of DNA and help in the mitotic activities. The genotoxic effect of the silk dyeing industry effluents induced micronuclei in the roots of Allium, indicating the efficiency of Allium MNC (Micro Nuclear) system in detecting clastogenic potential of the effluents. The present study reveals that if the effluents are released to the environment with dilution up to 30.0% then they will enhance the mitotic activities and thereby the growth of the plants. The higher concentrations of the effluents will harm the plans thereby reducing the mitotic activities
