We investigated the concentrations of beta-carotene, alpha-tocopherol, and retinol in obese children, together with assessment of the influence of relative body weight and plasma lipids. A lower plasma beta-carotene level was observed in the obese children, and plasma beta-carotene was inversely correlated with the relative body weight, but not with plasma total lipids. In contrast, the plasma alpha-tocopherol concentration was correlated with plasma total lipids, but not with the severity of obesity. Both the beta-carotene/plasma total lipids ratio and the alpha-tocopherol/plasma total lipids ratio were decreased in hyperlipidemic children, while there was a slight increase of the plasma retinol concentration. There was a marked elevation of the plasma beta-carotene concentration and a reduction of the alpha-tocopherol concentration corresponding to the changes of plasma lipids with diet and exercise. We conclude that different kinetics of the fat-soluble vitamins such as beta-carotene and alpha-tocopherol exists during dieting and exercise in obese children.