Sexually mature male Wistar rats (weighing 300-320 g and each group 6 animals) were given malathion (27 mg/kg; 1/50 of the LD50 for an oral dose) and/or vitamin C (200 mg/kg) + vitamin E (200 mg/kg) daily via gavage for 4 weeks. The sperm counts, sperm motility, sperm morphology, FSH, LH, and testosterone levels, and histopathological changes in the testes of these rats, were investigated at the end of the 4th week. By the end of 4th week, rats given malathion alone, or in combination with vitamins C and E, had significantly lower sperm counts and sperm motility, and significantly higher abnormal sperm numbers, than the untreated control rats. The rats given malathion alone or in combination with vitamins also had significantly lower plasma FSH, LH and testosterone levels than the control rats. Co-treatment of malathion-exposed rats with vitamins E and C had a protective effect on sperm counts, sperm motility and abnormal sperm numbers, but not on plasma FSH, LH and testosterone levels. Light microscopic investigations revealed that 4 weeks of malathion exposure was associated with necrosis and edema in the seminiferous tubules and interstitial tissues. Degenerative changes in the seminiferous tubules were also observed in the rats which received malathion and supplemented with vitamins C and E, but milder histopathological changes were observed in the interstitial tissues. Thus, it appears that vitamins C and E ameliorate malathion testicular toxicity but are not completely protective. (C) 2009 Elsevier Ltd. All rights reserved.