Serum total lipids, lipoprotein cholesterol, apolipoprotein A (Apo A), and liver function tests have been investigated in patients with acute viral hepatitis and chronic liver disease. Hypertriglyceridaemia, absence of alpha and pre beta bands on the lipoprotein electrophoresis pattern, low level of Apo A, and presence of abnormal lipoproteins (beta-VLDL and beta2-LP) were observed in the early phase of acute hepatitis. A positive correlation was found between Apo A and high-density lipoprotein cholesterol, and a negative one between Apo A and triglyceride, bile acids, total bilirubin, and serum alanine aminotransferase. Lipoprotein abnormalities found in the early phase of acute hepatitis are probably due to low lecithin-cholesterol acyltransferase activity. The reappearance of alpha lipoprotein and the increase of Apo A are sensitive indices of improvement of liver function. In chronic liver disease low levels of cholesterol and Apo A indicate the severity of liver cell injury.