CROCIN, the chief component of Crocus Sativus L. (Saffron), is well recognized for its antioxidant action by scavenging reactive oxygen species (ROS), particularly superoxide anion. In this research, 32 adult NMRI male mice were divided into four groups; control and the three experimental groups as crocin at 4, 20, and 100 mg/kg, and all doses were given to mice by gavage for six weeks. For histological study, tissue sections were stained by hematoxylin and eosin (H&E) and Masson's trichrome stains. The spermatogenesis indices include the repopulation index (RI), spermatogenesis index (SI), tubular differentiation index (TDI), and Sertoli cell index (SEI) were measured. Data was evaluated by one-way ANOVA, using SPSS software. The results of this study showed that crocin (100 mg/kg) significantly reduced the diameter of seminiferous tubules and the number of sperm in seminiferous tubules. The statistical analysis for TDI and SI in experimental groups presented that there was no significant difference in various doses of crocin, compared with the control group while, RI Data analysis showed that all administrated doses of crocin cleared significance to reduce it, compared with the control group. Also, the number of Sertoli cells significantly reduced in all treated groups with crocin. 
We concluded that crocin at the high dose of 100 mg/kg has some side effects on the reproductive system of mice while is relatively safer at doses of 4 and 20 mg/kg. Therefore, lower doses are suggested for further studies and possible clinical trials.