Genotoxic effects of agricultural chemicals are of special concern because of their generally irreversible effects and the long latency associated with their manifestation. These effects include heritable genetic diseases, carcinogenesis, reproductive dysfunction and birth defects. The present study was carried out to investigate the effect of the organophosphorous insecticide "profenofos" on white albino rats. The rats were treated for 28 days with three different doses of profenofos (1/20 LD50, 1/40 LD50, and 1/80 LD50). Then the animals were left without treatments for 14 days for possible recovery. The genotoxic effect of the pesticide was evaluated by using the micronucleus assay in the bone marrow and polymorphism of glutathione S-transferase (GST) by polymerase chain reaction (PCR). The results demonstrated that the treatment with profenofos caused a significant increase in the frequencies of micronucleated polychromatic erythrocytes. Results of polymorphism of both GSTM1 and GSTT1 showed positive genotype in the control group. While the results of GSTT1 polymorphism in the treated rats showed positive genotype in all doses of profenofos. The GSTM1 polymorphism showed positive genotype in the high and medium doses (1/20 LD50 and 1/40 LD50) but not in the low dose (1/80 LD50), where the GSTM1 was null (negative) genotype. After the recovery period the polymorphism of GSTM1 and GSTT1 was found to be positive genotype, except with the low dose (1/80 LD50) showed null genotype for GSTM1 gene. The histopathological data showed that profenofos exhibited histopathological changes in liver, kidney, spleen and tests. Liver showed hepatic cell damage with degenerative changes. The kidney showed heamorrhages, edema, necrosis and glomeruli shrinkage. The spleen showed slight deplesion of the lymphocytes of the white pulp. The tests showed interstitial edema and severe necrosis of spermatogenesis. From these results we concluded that the profenofos exert genotoxic and histopathological effects on albino white rats.