In the present study, the genotoxic effect of wastewater including heavy metals was investigated. For this purpose, the induction/reduction of mutation and recombination of surface water sampled before and after the discharge points (station-I,II) of the local fat plant (Erzurum, Turkey) were investigated by wing Somatic Mutation and Recombination Test (SMART) of the Drosophila melanogaster. In this study, thirdinstar larvae, which are trans-heterozygous for the third chromosome recessive markers with multiple wing hairs (mwh) and flare-3 (flr3) were separated into groups and were exposed to two different water samples including high and low metal ion concentrations. These larvae were kept in the culture media until the adult stage. Wing preparates of obtained adult individuals were prepared and examined under a light microscope. Frequencies of mutant clones formed through application of surface water samples taken from station I and station II in different periods and frequencies of the control group were compared by a Conditional Binominal Test. While it was observed that the samples taken from station I did not cause an increase in the total mutant clone frequency whereas the samples obtained from station II did. It was suggested that the metal ion concentration was determined to be higher in station II which might have lead to this result.