Objective To investigate the effects of Ethephon on spermatogenic cells and sex hormones levels of adolescentmalerats.Methods The male SD rats of 25-day old were randomly (from the random number table) divided into high dose group (2 000 mg/kg),middle dose group (1 000 mg/kg),low dose group (500 mg/kg) and control group (the same amount of physiological saline).They were given Ethephon through stomach for 14 d.The pathological changes in testistissues were observed by HE staining.The apoptosis of germ cells were detected by terminal transferase labeling (TUNEL).The automatic chemical luminescenceimmunoassay analyzer was used to test the serumsex hormone levels.Results After ethephon and saline lavage for 14 days in the dose of 2 000 mg/kg,1 000mg/kg,500 mg/kg concentrations respectively,body weightgrowth was significantly decreased (F =3.58,P =0.03).Testis mass growth [(0.91 ± 0.17) g,(1.13 ± 0.15) g,(1.21 ± 0.11) g,(1.29 ± 0.28) g] was significantly decreased (F =4.31,P =0.02).Experimental group spermatogenic cellapoptosis,the apoptosis index increased (F =156.00,P =0.00),high dose group[(2.40 ±0.18)%] and middle dose group[(1.72 ±0.14)%] was significandy increased (P < 0.01).The levels of testosterone and estrogen in serum showed a decreasing trend along with the increase of the doses,and there was a statistical significance (F =11.85,38.93,all P =0.00).Compared with the control group [(0.86 ± 0.10) μg/L],the testosterone levels in high dose group [(0.31 ± 0.08) μg/L],middle dose group [(0.36± 0.05) μg/L] decreased significantly (P < 0.01).Compared with the control group,low dose group,middle dose group [(36.43 ± 3.57) ng/L,(38.62 ± 2.24) ng/L,(31.87 ± 5.78) ng/L],the estrogen level in high dose group[(27.39 ± 2.11) ng/L] was significantly reduced (P < 0.01).Conclusion Ethephon has reproductive toxicity,and can cause the serum level of testosterone and estradiol decreased,resulting in spermatogenic cellapoptosis index increased and the spermatogenic capability decreased.