['To examine serum leptin concentrations in obese and lean patients with polycystic ovary syndrome (PCOS) to assess whether the changes in leptin levels are due to obesity or hormonal alterations.', 'Controlled clinical study.', 'Academic research environment.', 'Obese and lean women with PCOS.', 'Blood samples were collected before and after food consumption.', 'Serum leptin and insulin levels.', 'Serum leptin concentrations were significantly correlated with body mass index (r = 0.649) and also with HOMA (r = 0.535). However, after controlling for body mass index in a partial correlation analysis, no significant correlation was found between serum leptin levels and HOMA or hyperinsulinemia. While lean patients with PCOS had a significant correlation between leptin concentrations and obesity parameters, they did not show any significant correlation with insulin resistance parameters.'] Do serum leptin levels correlate with obesity parameters but not with hyperinsulinism in women with polycystic ovary syndrome?