Objectives:To investigate in vivo the effects of zinc oxide(ZnO) nanoparticles on the main organs of female mice, especially on female reproductive system. Methods:Female mice, aged 5 weeks, were intraperitoneally injected with 200 and 500 mg/kg of zinc oxide(ZnO) nanoparticles, respectively, every other day for 5 times. Control group was injected with equal volume of normal saline. After one week of treatment, the coefficients of organs serum biochemical parameters and gonadal hormone(E2 and P) in female mice intraperitoneally treated with ZnO nanoparticles were measured. Main organs were observed in pathology. Results:Compared with control group, the coefficients of kidneys and ovaries were significantly changed in both 200 mg/kg group and 500 mg/kg group, and the coefficients of heart was significantly changed in 200 mg/kg group. The changes of coefficients of liver(P < 0.05) suggested the small hepatic injury after treatment with ZnO nanoparticles. UA in both groups raised significantly(P < 0.05), showing that ZnO nanoparticles had small nephrotoxicity after treatment with ZnO nanoparticles. The significantly change of serum LDH in both groups(P < 0.05) suggested the limited myocardial damage compared with the control group. However, there were no significant changes in pathological observation of main organs, including ovaries and uterus. The level of E2 and P were not significantly changed by the treatment with two doses of ZnO nanoparticles. Conclusions:There were slight damage in the function of liver, kidneys and heart with large dose of ZnO nanoparticles. However, there were no significant effect on the levels of E2 and P and pathology of ovaries. In conclusion, ZnO nanoparticles under 500 mg/kg dose was safe for reproductive system.