Purpose: In this rearch, we made a plan to investigate the effects of Changbuyeukgun-Tang(CET) on the polycystic ovary(PCOS) induced by estradiol valerate(EV) in rats. PCO was induced by single intramuscular injection with EV(4㎎) in female rats. Rats(n=8) in normal group were injected with sesame oil and orally administrated distilled water for 8weeks Rats in PCO control group(n=8) were injected with EV and orally administrated distilled water for 8weeks. Rats in CET treated group(n=8) were injected with EV and orally administrated CET for 8weeks. Methods: We measured the weights of the body, the ovary, the uterus and the adrenal gland. And also, we analyzed ovarian histopathology, NGF and CRF immunohistochemistry. Results: The results were as follows1. the weights(㎎) of the ovaries in CET treated group were significantly increased(p<0.001) compared with PCO control group. 2. the number of the mature follicles in CET treated group were significantly increased(p<0.01) compared with PCO control. 3. the number of the atresia follicles in CET treated group were significantly decreased(p<0.01) compared with PCO control. 4. the number of the corpora in CET treated group were significantly increased(p<0.05) compared with PCO control. 5. the expressions of NGF-immunoreactive cells in the ovarian granulosa cells of rats in CET treated group were less observed than PCO control group. Conclusion: According to these results, we finally concluded that Changbuyeukgun-Tang(CET) has the inhibitory effect on the development of EV-induced polycystic ovary. And we deduced that the effect of it may be related to the decreased NGF activities in the ovary.