Abstract Background & Aims: Sodium arsenite causes oxidative stress and endocrine disorders in the reproductive system. The aim was to investigate the protective role of curcumin as an antioxidant on the seminal vesicle tissue in adult mice treated with sodium arsenite. Materials & Methods: Adult male Naval Medical Research Institute (NMRI) mice were randomly divided into 4 groups (six mice per group) including control, Sodium arsenite (5mg/kg/day b.w.), Curcumin (15mg/kg/day b.w.) and Sodium arsenite + Curcumin. After 5 weeks of treatment, the mice were anesthetized and the seminal vesicles were removed and weighed. This followed by evaluating of the mean total volume of seminal vesicle and the mean volume of parenchyma, vesicular fluid, epithelial cells, vessels, connective and muscular tissues using stereological techniques. The results analyzed statistically by one-way ANOVA and Tukey's test and the means were considered significantly different at p<0.05. Results: A significant reduction in the mean total volume of seminal vesicle and mean volume of vesicular fluid (p<0.001), and a significant increase in the mean volume of connective tissue (p<0.001) were seen in the sodium arsenite group when compared to the control ones. The mentioned parameters were compensated to the control level in the sodium arsenite + curcumin group. Conclusion: Our results showed that curcumin could prevent the adverse histological changes induced by sodium arsenite treatment on the seminal vesicle in mice.