Purpose: The incidence of polycystic ovary syndrome (PCOS) increases in women with epilepsy (WWE), which appears to vary with ethnicity. This study was conducted to determine the incidence and risk factors of PCOS in Chinese WWE. Methods: The study was carried out in 102 of 139 Chinese WWE at reproductive ages, with 32 receiving valproic acid (VPA), 40 receiving other antiepileptic drugs (AEDs), and 30 without AEDs therapy. PCOS was defined as having 2 or more of the following components: polycystic ovaries, hyperandrogenism, and amenorrhoea or oligomenorrhoea (a/oligomenorrhoea). Results: One or more isolated components of PCOS were found in 56 (54.9 ) patients, with 29 (28.4 ) having polycystic ovaries, 20 (19.6 ) with a/oligomenorrhea, 7 (6.9 ) with hyperandrogenism, and 13 (12.7 ) with defined PCOS. Their average age at the start of seizure was 13.8 6.5 years, younger than that of patients without these disorders (16.9 8.6 years, p <0.05). VPA therapy increased the incidence of PCOS (11/32, 34.4 ), in addition to increased blood levels of testosterone and luteinizing hormone (LH) as well as LH to FSH (follicle-stimulating hormone) ratio. No significant relationship was found between the incidence of PCOS and the type, duration, or frequency of seizures in these WWE. Conclusion: There is an increased incidence of PCOS in Chinese WWE at reproductive ages, by more than 2 times of that in the general population. Risk factors include seizures starting at a young age and VPA therapy.