Aim: To find out the effect of lindane on testicular antioxidant system and testicular steroidogenesis in adult male rats. Methods: Adult male rats were orally administered with lindane at a dose of 5.0 mg/kg body weight per day for 30 days. Twenty-four hours after the last treatment the rats were killed using anesthetic ether. Testes, epididymis,seminal vesicles and ventral prostate were removed and weighed. A 10% testicular homogenate was prepared and cen trifuged at 4°C. The supematant was used for various biochemical estimations. Results: The body weight and the weights of testes, epididymis, seminal vesicles and ventral prostate were reduced in lindane-treated rars. There was asignificant decline in the activities of antioxidant enzymes superoxide dismutase (SOD), catalase and glutathione reduc tase while an increase in hydrogen peroxide (H2O2) generation was observed. The specific activities of testicular steroidogenic enzymes 3β-hydroxysteroid dehydrogenase and 17β-hydroxysteroid dehydrogenase were decreased. The levels of DNA, RNA and protein were also decreased in lindane-treated rats. Conclusion: Lindane induces oxida tive stress and decreases antioxidant enzymes in adult male rats.