Phosphamidon(PMD) is orgnophosphate insecticide broadly using in agriculture. In order to study PMD toxicity in the testis, histopathological change and apoptosis were assessed following acute and chronic oral administration in rats and chickens. In acute studies, histopathological changes included necrosis and desquamation of spermatogenic cells, multinucleated giant cells in the lumen of seminiferous tubules, and necrotic cells and the giant cells in the epididymal lumen. Atrophy of seminiferous tubule was seen in the chronic exposure with low doses. The toxic effects of PMD in chronic exposure including clinical signs and histopathological changes were more pronounced in chickens than rats. Apoptosis assessment was performed by TUNEL method and Hoechst staining. TUNEL-positive apoptotic cells were found in spermatocytes of seminiferous tubules, testicular apoptosis was more prominent following acute exposure than control and chronic exposure. Above mentioned result noticed that PMD causes apoptotic death and effects directly the spermatocytogenesis.