Background: Cyclophosphamide, a widely used anticancer drug, carries significant pharmacological benefits but also in- duces oxidative stress in tissues, particularly affecting the testis and sperm parameters. This study aimed to explore selenium impact on the sperm parameters in adult mice undergoing cy- clophosphamide treatment. Materials and Methods: We randomly divided 36 adult NMRI male mice into four groups: control, cyclophosphamide (100 mg/kg/bw/week), selenium (1 mg/kg/bw/day), and cyclophos- phamide + selenium, treating them for 35 days. After dissecting the mice, we cut the caudal region of the testicular epididymis in ham's F 10 culture medium to collect ejected sperm for eval- uating sperm parameters. Data were analyzed using one-way ANOVA and Tukey’s test, and the means were considered sig- nificantly different at P<0.05. Results: The group treated with cyclophosphamide exhibited a significant decrease in the mean sperm count, percentage of motility, viability, sperm membrane integrity, and the normal sperm morphology compared to the control group (P<0.001). The cyclophosphamide + selenium group showed a significant increase in the mentioned parameters compared to the cyclo- phosphamide group (P<0.001). The means of the sperm param- eters in the selenium group were the same as the control group when compared to those (P>0.05) Conclusion: Our findings indicate that selenium, acting as a potent antioxidant, can reduce cyclophosphamide's negative impact on sperm parameters by alleviating oxidative stress.
