Aim:To investigate the effect of formaldehyde(FA)on testes and the protective effect of vitamin E(VE)againstoxidative damage by FA in the testes of adult rats.Methods:Thirty rats were randomly divided into three groups:(1)control;(2)FA treatment group(FAt);and(3)FAt+VE group.FAt and FAt + VE groups were exposed to FA byinhalation at a concentration of 10 mg/m~3 for 2 weeks.In addition,FAt+VE group were orally administered VE duringthe 2-week FA treatment.After the treatment,the histopathological and biochemical changes in testes,as well as thequantity and quality of sperm,were observed.Results:The testicular weight,the quantity and quality of sperm,theactivities of superoxide dismutase(SOD),glutathione peroxidase(GSH-Px)and glutathione(GSH)were significantlydecreased whereas the level of malondialdehyde(MDA)was significantly increased in testes of rats in FAt groupcompared with those in the control group.VE treatment restored these parameters in FAt+VE group.In addition,microscopy with hematoxylin-eosin(HE)staining showed that seminiferous tubules atrophied,seminiferous epithelialcells disintegrated and shed in rats in FAt group and VE treatment significantly improved the testicular structure in FAt+VE group.Conclusion:FA destroys the testicular structure and function in adult rats by inducing oxidative stress,and this damage could be partially reversed by VE.(Asian J Androl 2006 Sep;8:584-588) Aim: To investigate the effect of formaldehyde (FA) on testes and the protective effect of vitamin E (VE) against oxidative damage by FA in the testes of adult rats. Methods: Thirty rats were differentiated into three groups: (1) control; (2) FA treatment group (FAt); and (3) FAt + VE group. FAt and FAt + VE groups were exposed to FA byinhalation at a concentration of 10 mg / m ~ 3 for 2 weeks.In addition, FAt + VE the group was orally administered VE during the 2-week FA treatment. After the treatment, the histopathological and biochemical changes in testes, as well as the quantity and quality of sperm, were observed. Results: The testicular weight, the quantity and quality of sperm, theactivities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and glutathione (GSH) were significantly decreased creased in the level of malondialdehyde (MDA) was significantly increased in testes of rats in FAt group compared with those in the control group. parameters in FAt + VE group. addition, microscopy with hematoxylin-eosin (HE) staining showed that seminiferous tubules atrophied, seminiferous epithelial cells were disintegrated and shed in rats in FAt group and VE treatment significantly improved the testicular structure in FAt + VE group. Confc: FA destroys the testicular structure and function in adult rats by inducing oxidative stress, and this damage could be reversed, by vE. (Asian J Androl 2006 Sep; 8: 584-588)