Excessive alcohol ingestion results in profound derangements of lipid and lipoprotein metabolism, reflecting the effects of ethanol on peripheral and hepatic lipid metabolism and its toxic effects on hepatic function. The alterations in plasma lipids and lipoproteins are secondary to complex abnormalities of lipoprotein synthesis, secretion and catabolism. The major effects of alcohol include fatty liver secondary to excessive triglyceride synthesis, resulting in an imbalance between synthesis and hepatic secretion; hypertriglyceridemia and hypercholesterolemia; defective plasma cholesterol esterification; and decreased high-density lipoprotein cholesterol. In patients with severe alcoholic hepatitis, the plasma lipoproteins have an abnormal structure and apoprotein composition. Although these changes are usually reversible with abstinence from alcohol (if liver function returns to normal), they indicate serious effects of alcohol on the liver, which may culminate in cirrhosis and hepatic insufficiency. These effects of alcohol on lipids and lipoproteins should be contrasted with the elevation in high-density lipoprotein cholesterol concentration produced by moderate alcohol intake and the possibility that this increase may protect against the development of atherosclerotic disease.