One of the important etiologic factors in acne is an increase in sebaceous gland activity, which is androgen dependent. Acne is a common manifestation of hyperandrogenemia. Therefore, acne may not only cause cosmetic concern but may also be a sign of underlying disease. In females, the most common cause of hyperandrogenemia is polycystic ovary syndrome (PCOS). The purpose of this study was to determine the hormonal profiles of women with acne and the prevalence of PCOS in women attending the dermatological clinic with acne problems. The diagnostic criteria of PCOS were clinical findings of menstrual disturbances and hyperandrogenism (acne, seborrhea, hirsutism), pelvic ultrasound imaging of PCO (multiple subcapsular ovarian cysts 2-8 mm. in diameter, with dense echogenic stroma), and an elevated luteinizing hormone (LH) to follicle stimulating hormone (FSH) ratio. There were 51 women with acne; 20 regularly menstruating volunteers without acne served as a control group. PCOS was found in 19 out of 51 patients with acne (37.3%) and none of the control group. Twenty acne patients had abnormal menstruation (39.2%). Acne cases had higher mean levels of serum total testosterone (T), free T, dehydroepiandrosterone sulfate (DHEAS) and prolactin (PRL). No statistically significant difference was observed for LH, FSH or sex hormone binding globulin (SHBG). Because of this high prevalence of PCOS in women with acne, all women presenting with acne should be asked about their menstrual pattern and examined for other signs of hyperandrogenemia. Hormonal profile determination as well as pelvic ultrasonography for ovarian visualization should be performed to confirm the diagnosis of PCOS in female acne patients who have menstrual disturbances.