OBJECTIVE Based on the role of polycystic ovary syndrome as a cause of metabolic syndrome with chronic anovulation, obesity, hyperinsulinemia and hyperandrogenism, development of effective treatment for its obesity is a priority. METHODS We designed a study, involving 52 patients of 19-36 years of age, to test the pioglitazone in women with polycystic ovary syndrome. Subjects were assigned to receive pioglitazone for 3 months. Body mass index, waist circumference and hip circumference were measured before and after 3 months of pioglitazone prescription. RESULTS Fifty patients completed the study. No complication reported during the study period. Waist circumference, hip circumference and waist to height ratio decreased significantly. Body weight and body mass index increased. No significant improvement was seen in acne, acanthosis, hirsutism and menstrual irregularities. CONCLUSIONS Pioglitazone has beneficial effects on central obesity of the patients with polycystic ovary syndrome but other clinical consequences of the syndrome may not improve with the drug.