Electron microscopic studies were performed on spermatozoa from the lumen of cauda epididymis in rats receiving lead acetate (II) for a period 5-fold longer than one spermatogenesis. There were numerous ultrastructural changes of spermatozoa. Mitochondrial spiral, outer dense fibers and axoneme were affected. Based on the present results it may be suggested that lead can damage spermatozoa in the epididymis.