Genistein is a phytoestrogen that aquatic environment contaminant and is found in a wide variety of plant-derived foods especially in soybeans and soy-based foods. In this study, the potential genotoxic effects of genistein which available from several factories waste were researched via using Drosophila wing somatic mutation and recombination test (SMART). Third-instar larvae trans-heterozygous for two genetic markers mwh and flr, were treated by different concentrations (1, 3, 5 ve 10 mu M) of genistein. According to our results, depending on the concentration increased, especially in small single type, the total mwh and the total clones positive results were observed. Consequently, the results of this study indicate that genistein was highly genotoxic in the SMART assay.