['To determine whether or not serum adiponectin concentrations are influenced by ovarian hyperstimulation during in vitro fertilization (IVF).', 'This study involved 52 women who were participating in IVF-ET cycles. Adiponectin levels in serum were determined by radioimmunoassay and compared.', 'Serum adiponectin levels fell from Day-basal to Day-hCG (p = 0.047), and then rose on Day-OR and again on Day-7ET (p < 0.001; p < 0.001). Estradiol levels on Day-hCG were significantly and positively correlated with serum adiponectin levels on Day-OR and Day-7ET (r = 0.325, p = 0.019; r = 0.372, p = 0.007). Progesterone levels on Day-OR positively correlated with serum adiponectin levels on Day-basal (r = 0.278, p = 0.046). There was also a positive correlation between progesterone levels on Day-7ET and serum adiponectin levels on Day-OR (r = 0.289, p = 0.038). Multiple linear regression analysis revealed that adiponectin levels on Day-OR and Day-7ET were negatively correlated with age and body mass index after adjustment was made for concomitant diseases.'] Do serum adiponectin levels increase after human chorionic gonadotropin treatment during in vitro fertilization?