Background and aims: It has been suggested that adipokine changes might precede changes in plasma non-esterified fatty acids and other obesity metabolic biomarkers. The aim of the present study was to evaluate changes in fasting and postprandial plasma levels of adiponectin, non-esterified fatty acids, and tumor necrosis factor-alpha in prepubertal obese children and age-matched normal-weight children. Methods and results: Fifty-four children of prepubertal age (34 obese, comprising 23 males and 11 females, and 20 normal-weight comprising 11 males and 9 females) were studied. A standard 438 kcal breakfast was given to both groups. Baseline measurements included anthropometry and plasma lipids. The following parameters were determined in plasma before and after breakfast: glucose, insulin, and C-peptide at baseline and 2 h and non-esterified fatty acids, adiponectin, and tumor necrosis factor-alpha at baseline and 1, 2, and 3 h. Fasting plasma non-esterified fatty acid levels were lower in the obese versus normal-weight children (P = 0.021). Both at baseline and postprandially, plasma adiponectin levels were lower in the obese versus normal-weight children (P < 0.001). A trend was observed (P = 0.06) that levels of tumor necrosis factor-alpha were lower in the obese versus normal-weight children. Adiponectin was inversely associated with insulin in the obese children after adjustment for BMI and sex (r = -0.401, P = 0.025). Conclusion: At prepubertal age, obese children show lower fasting and postprandial plasma adiponectin levels in comparison to normal-weight children, whereas non-esterified fatty acids and tumor necrosis factor-alpha were not yet increased. Therefore, adiponectin appears to be a good marker of early metabolic alterations associated with childhood obesity. (C) 2009 Elsevier B. V. All rights reserved.