Abstract Plasma lipids and 6 plasma apolipoproteins (apoA-I, apoA-II, apoB, apoC-I, apoC-II and apoC-III) were studied in 23 patients with nephrotic syndrome. The elevated total cholesterol, triglyceride and apoB levels in nephrotic patients decreased gradually, after the disappearance of proteinuria. During the acute stage high density lipoprotein cholesterol, as well as the sum of apoA-I and apoA-II were similar in the patients and the controls. ApoA-I and apoA-II were transiently elevated during the recovery stage. All three apoC proteins (apoC-I, apoC-II and apoC-III) were elevated during the acute stage. A significant decrease in apoC-I, apoC-II and apoC-III was observed during the first 3 weeks after normalization of the urine protein. The ratio of apoC-II/apoC-III was reduced during the first 4 weeks after normalization of urine protein and then returned to the control level. The results suggest that as far as total levels are concerned, changes of apoC-II, apoC-III and the ratio of apoC-II/apoC-III appear to have no effect on the development of hyperlipidemia in the nephrotic syndrome.