Changes in plasma lipoprotein pattern, with particular attention to high density lipoprotein cholesterol (HDL-C) concentration, were evaluated in 7 (5 female, 2 male) obese patients before and 15 +/- 1 months after they had lost weight (mean 20.7 +/- 3.1 kg), when the patients' food intake had been ad libitum for at least 6 months, and they had been maintaining their weight loss. Plasma low density lipoprotein cholesterol (LDL-C) and very low density lipoprotein triglyceride (VLDL-TG) concentrations were lower than baseline values: on the other hand, plasma HDL-C concentration, which was below normal values before weight reduction, was found to be significantly increased (P < 0.05). These data indicate that, among the favourable changes in plasma lipoprotein pattern, an increase in HDL-C may be achieved after remarkable and stable weight loss in severe obesity.