Purpose: Polycystic ovary syndrome(PCOS) is a common condition characterised by menstrual abnormalities. PCOS is now recognised to be a metabolic syndrome which may include hyperinsulinemia, hyperlipidemia, diabetes mellitus and possibly cardiac disease. Cyperi Rhizoma(CR) can soothe the liver to regulate gi and regulate menstruation to relieve pain. For these reasons, this study was designed to investigate the effects of CR on metabolic syndrome in PCO rats. Methods: Female rats injected with a single dose of 2 mg/kg estradiol valerate (EV) develop PCO, CR was given for 5 weeks. After 5 weeks administration of drugs, body weights, food uptake, Fasting Blood Glucose, Oral Glucose Tolerance Test, Total Cholesterol, HDL-Cholesterol, LDL-Cholesterol and Triglyceride were measured once a week. Results: In this experiment, single injection of EV induced hyperlipidemia, but it did not affect serum glucose levels. Oral administration of CR prevent weight loss shown in control group. In addition, treatment with CR can lower total cholesterol, LDL-cholesterol and triglyceride in serum compared to PCO induced control group. Conclusions: These results suggest that CR can regulate hyperlipidemia in PCOS.