Forty-two patients with the nephrotic syndrome were grouped according to the absence or presence of renal failure and/or diabetes mellitus. All patients had a similar degree of hypoalbuminemia and urinary protein losses. A lipid and apoprotein pattern was generated in serum and ultracentrifugally isolated lipoproteins. Low-density lipoprotein composition was essentially normal in uremic patients while in the other patients with the nephrotic syndrome, a considerable lipid enrichment was noted. The very-low-density lipoprotein content in lipids was uniformly increased in nephrotic patients irrespective of the presence of complications. High-density lipoprotein cholesterol and serum apolipoprotein A I and E concentration was significantly reduced in uremic patients with respect to normal subjects and to the other groups considered. Serum apolipoprotein A II and B levels were also decreased in uremics. All patients had increased serum apoprotein C II and C III concentration. We conclude that diabetes mellitus does not affect the pattern of hyperlipoproteinemia of nephrotic syndrome while the characteristic lipoprotein and apoprotein pattern of uremia is present irrespective of nephrosis in uremic, nondiabetic patients.