In this study, different concentrations of some organophosphate insecticides (methyl parathion, azamethiphos, dichlorvos and diazinon) have been evaluated for genotoxicity in the wing somatic mutation and recombination test (SMART) of Drosophila melanogaster. Third-instar larvae trans-heterozygous for two genetic markers mwh and flr, were treated at different concentrations (1 ppm, 3 ppm, 5 ppm, 7 ppm, 10 ppm) of the test compounds. A positive correlation was observed between total mutations and the number of wings having mutations. In addition, the observed mutations were classified according to size and type of mutation per wing. Chemicals used were ranked in decreasing order according to their genotoxic effects as diazinon, dichlorvos, methyl parathion, azamethiphos. © 2004 Elsevier Ltd. All rights reserved.