Objective: Citrullus lanatus is an antioxidant and it has been shown to reduce oxidative stress. Previous study confirmed antioxidants have essential effect on infertility by their role on reactive oxygen’s spaces. Materials and Methods: Wistar male rat (n=20) were allocated into two groups, control group (n=10) and C. lanatus group that received 30 mg/kg, (n=10), by gavage method, daily for, 4 weeks, respectively; however, the control group just received an equal volume of distilled water daily. Animals were kept in standard condition. In 28 day, for measurement blood glucose and TESTOSTERONE, 5 cc blood of each rat were collected then prepared for analysis.Results: Serum TESTOSTERONE significantly was increased in group that has received 30 mg/kg of extract, (P<0.05) in comparison to control group (P<0.05). Blood glucose was decreased in extract group but was not significantly when compared to control group (P>0.05).Conclusion: Since in our study 30 mg/kg C. lanatus has significantly increased serum TESTOSTERONE and hence it seem this results can beneficial effects on fertility and need more evaluations in next researches.