Recent evidence has indicated that exercise as well as ethanol exerts oxidative stress on vital organs/tissues of the body. However, the combination of both on the testicular antioxidant system is not known. This study investigates the interactive effects of exercise training and chronic ethanol ingestion on the testicular antioxidant system in rats. Male Fisher-344 rats were treated as follows: sedentary control (SC); exercise training (ET) for 6.5 weeks; ethanol (2 g kg(-1), p.o.) for 6.5 weeks; and ET plus ethanol for 6.5 weeks. Exercise training significantly decreased copper-zinc superoxide dismutase (CuZn-SOD) activity and enzyme protein concentration (73% and 67% of SC), whereas manganese SOD (Mn-SOD) and catalase (CAT) activity significantly increased (157% and 141% of SC) in the testes of rat. Exercise training significantly decreased the testicular malondialdehyde (MDA) concentration (70% of SC). Chronic ethanol ingestion significantly decreased testicular CuZn-SOD activity, enzyme protein concentration and CAT activity (65, 70 and 47% of SC) in rats. Ethanol significantly increased the testicular MDA level (129% of SC). The combination of exercise training and chronic ethanol ingestion significantly decreased testicular CuZn-SOD protein, MDA and the reduced glutathione oxidized glutathione ratio (GSH/GSSG) by 62, 70 and 79%, respectively. The data suggest that exercise training provides protection whereas chronic ethanol ingestion exerts oxidative damage to the testes of rat. Exercise training seems to reduce the extent of oxidative damage caused by ethanol on the testes of rats.