Objective: Celecoxib is a nonstroidal anti-inflammatory drug .This is a selectiveCox-2 inhibitor.Nowadays this drug uses as an analgesicantipyretic and anti-inflammatory agent frequently. In some patients that used celecoxib for a long time unusual effect of this drug may be seen. The goal of this survey is assess the effect of this drug on male-reproductive system functions Materials and Methods: This survey done for study of effect of celecoxib on rat reproductive system specially on spermatogenasis and the level of blood testosterone hormone. In this manner histologic studies and measuring of weight (testis prostate seminal vesicle and epidydimis) and the level of blood testestron are done. 50 rat with 200-230 gr. weight selected and compared in 5 groups.control group (no drug given) sham group (solvent drug: Di- methyl sulfoxide) 3 cases group (orally celecoxib 10 20 and 40 mg/kg given daily) for 15 days. In the end of 15 days heart blood sampling for measuring serum testestron level accomplished after that reproductive systems separated and prepared for histologic study. Results: Result showed no significant differences in mean weight of body testis epidydimis and seminal vesicle in control and case groups. But significant differences are seen in the mean weight of prostate per body weight in case group (40 mg/kg) in compared with control group. That is due to antimalignant effect of celecoxib on prostate. No differences seem between control and case groups in arrangement mode nuclei shape and cytoplasm in histologic examination in spermatogonia and primary spermatocytes in transverse section of seminiferous tubules celecoxib in case group (40 mg/kg) can decrease lydige cells number that is due to inhibited prostaglandin synthesise for the result of cox-2 inhibitor and decreased level of testosterone hormone. Conclusion: It looks that number of sertoli cells in control and case groups are differences. So that in case group (40 mg/kg) number of sertoli cell’s decreased due to decrease testestron level. This can cause production of abnormal sperms. In the survey can conclude that use of high doses of celecoxib can decreased size and number of lydig cells and this is cause of decreased testosterone hormone.