Serum adiponectin levels were evaluated in 60 women with polycystic ovary syndrome (PCOS), 30 normal-weighted and 30 obese women, and 60 healthy women age and body mass index (BMI) matched with the patients. The homeostasis model assessment (HOMA) score was also calculated. Both in PCOS and controls, serum adiponectin levels were significantly (P < 0.05) lower in obese than normal-weight women, without any difference between PCOS and controls. The HOMA score was significantly (P < 0.05) higher in obese than normal-weight women both in PCOS and controls; additionally, the HOMA score was significantly (P < 0.05) higher in normal-weight PCOS than normal-weight controls. Both in PCOS and controls, adiponectin levels were significantly correlated with BMI (r = -0.51, P < 0.01 in PCOS; r = -0.45, P < 0.01 in controls) and HOMA values (r = -0.39, P < 0.05 in PCOS; r = -0.35, P < 0.05 in controls); HOMA was correlated with BMI (r = 0.51, P < 0.01 in PCOS, r = 0.61, P < 0.001 in controls). In conclusion, our results confirm that adiponectin concentrations change according to variations of fat mass. They further suggest that insulin sensitivity per se probably does not play any pivotal role in the control of adiponectin levels in PCOS women.