Exposure to dexamethasone leads to numerous changes in the reproductive system. The aim was to evaluate the protective effect of vitamin C (Vit C) on spermatogenesis indexes and sperm motility in Mice following dexamethasone administration. 24 mice were divided into 4 groups: control, dexamethasone (7mg/kg/day), vitC (100mg/kg) and VitC+ dexamethasone and treated for 7 days with intraperitoneal injections. Spermatogenesis indexes, sperm motility, levels of malondialdehyde (MDA) and testosterone were evaluated.The results were analyzed by one-way ANOVA and Tukey's test and the means were considered significantly different at p<0.05. A significant increase in tissue and serum levels of MDA (p<0.001) and a significant decrease in Tubular differentiation index (TDI), Meiotic index (MI), spermiogenesis index (SPI) (p<0.001), and serum testosterone levels (p<0.002) and sperm motility (p<0.001) were found in the dexamethasone group compared to the control group. In the dexamethasone +vit C group, the spermatogenesis indexes, serum testosterone levels and sperm motility increased and serum level of MDA significantly decreased compared to the dexamethasone group. Our results indicate that VitC could reduce the dexamethasone induced toxic effects on the reproductive system. Therefore the indication of VitC in medical regimens including dexamethasone is suggested.