Background: Cadmium chloride which is potentially toxic is currently used in industry. The toxic effects of cadmium on testes have been reported to range from apoptosis to necrosis, with different effects on fertility. This research aimed to study the effect of different doses of cadmium on testicular tissues at acute stage by light and electron microscopy. Methods: Cadmium chloride was injected into mature Balb/c mice intraperitoneally in 7 doses. Five mice were studied in each group. After 48 hr, the testes were extracted and prepared for light microscopy. Then two concentrations (15 and 25 µM/kg) of them were selected for electron microscopic study based on histological changes. The cellular changes of luminal epithelium of seminiferous tubules were studied under an electron microscope. Histological and ultrastructural changes were reported. Results: The absence of sperm in the tubules was observed at 20 µM/kg concentration. At 25 µM/kg, histological destruction and epithelial damages were observed. Histological changes were not remarkable at 5 and 10 µM/kg. However, ultrastructural changes of seminiferous tubules at 20 µM/kg included spermatogonial cell death. At 25 µM/kg, vacuolation of Sertoli cells and death of spermatids as well as spermatocytes were observed. Cell death in the tubules was limited to germ cells. However, Sertoli cells exhibited architectural alterations without any cell death. Conclusion: Both apoptosis and necrosis occurred in testicular tissue by exposure to cadmium in a concentration-dependent manner. Gonadal cells were sensitive to cadmium administration. Supportive cells such as Sertoli cells in seminiferous tubules did not exhibit sensitivity to cadmium.