Abstract: Objective To study the effects of cadmium exposure on expression of hormone,including estradiol(E₂) and progesterone(P₄) and follicle development and to elucidate whether cadmium has toxicity in immature ovary.Methods Totally 48 Wistar rats were exposed to cadmium by intraperitoneal injected at the dose of 0,0.1,0.3 and 0.9 mg Cd²⁺/kg body weight,once a day for 19 days.After the exposure,the rats' ovaries were prepared to detect expression of follicles.The sera of the rats were sampled to determine E₂ and P₄ levels.Results E₂ levels in each dosage groups (6.04 ±0.28,6.10 ±0.1,and 5.96 ±0.18 pg/mL) were statistically significantly lower than that of the control group (6.62 ±0.24 pg/mL,P<0.05).The follicle expression in 0.9 mg Cd²⁺/kg group was different from that of the control group(P< 0.05).Conclusion Cadmium has obvious toxicity to immature female ovary development.