The plasma lipid and apoprotein concentrations were monitored in a group of 12 patients with chronic alcohol abuse entering an abstinence program for 3 weeks. 6 of them had a normal liver function as expressed by the levels of liver enzymes gamma GT, GOT, GPT, while 6 had elevated plasma liver enzyme concentrations. None had evidence of either cirrhosis or alcohol hepatitis. Patients with abnormal liver enzymes had elevated HDL-cholesterol, apo AI and apo AII concentrations in plasma, with normal total cholesterol and apo 8 concentrations. In the group of patients with normal liver enzyme concentrations, the apoproteins and lipids did not significantly differ from the control group. In the course of the abstinence treatment a parallel decrease of apoproteins, HDL-cholesterol and liver enzyme concentrations was observed. The values normalized after 10-15 days. These data indicate that the effect of alcohol on the plasma apoprotein and lipids occurs mostly in the HDL fraction, that it correlates with the state of hepatic function and that it can be reversed by an abstinence treatment.