This study was to elucidate DNA damage in rats treated with sodium fluoride (NaF) by performing 8-Hydroxy-2-deoxyguanosine (8-OHdG) immunohistochemical staining assays on seminiferous tubules of rats’ testis, and also to evaluate the protective effects of N-acetylcysteine (NAC) on spermatogenesis. Male Sprague Dawley (SD) rats were exposed to a single dose of NaF (25mg/kg/day) with or without NAC (150mg/kg/day) for 7 weeks (7W) by gastric gavage. Testicular fluorine content was detected by fluorine ion selective electrode method. Oxidative damage to DNA was evaluated by measuring the increase in 8-OHdG formation in testicular tissue through immunohistochemical staining assays and also the effects of NAC pretreatment. The biochemical indicators about oxidative stress were detected by colorimetric assays, sperm parameters and the morphological changes of testis were studied. NaF significantly increased serum levels of oxidative stress, markedly elevated testicular fluorine and 8-OHdG expression levels as well as the rate of sperm aberration compared to saline group. Testosterone in serum, sperm counts and the mobility of sperm were lower than those of the rats in control group. The pathological morphological changes in testicular seminiferous tubule were also obvious in the rats with NaF treatment. Pretreatment with NAC did not reduce the contents of fluoride content in testis, but significantly reduced 8-OHdG formation and lipid peroxidation. This study suggests that NAC may have certain antagonism on the reproductive damage induced by NaF.