This study was conducted to investigate the mechanism of lead (Pb)-induced testicular toxicity. We examined the impact of Pb toxicity on 17β-oestradiol (E2), oestrogen receptors (ERs) and aromatase P450 which are key factors in spermatogenesis. Treatment of rats with Pb acetate (PbAc, 50 mg/L in drinking water) significantly reduced sperm count, motility, viability and increased sperm abnormalities along with degenerative changes in seminiferous tubules and Leydig cells. Additionally, administration of PbAc resulted in a significant reduction in serum testosterone, serum and testicular E2 as well as increased level of testicular testosterone. Pb also induced testicular oxidative stress as evidenced by a significant decrease in the activities of superoxide dismutase, glutathione peroxidase and catalase antioxidant enzymes, and increased malondialdehyde level in the testis. At the molecular level, Pb treatment downregulated the mRNA expression of P450 arom (Cyp19) and ERα. In conclusion, Pb induces testicular oxidative damage and disrupts spermatogenesis, at least in part, via downregulation of Cyp19 and ERα expression, which further decrease E2 level. These data, therefore, provide insight into the mechanism of lead-induced testicular toxicity.