GGT (gammaglutamyl-transpeptidase) activity and HDL (high density lipoprotein) cholesterol were assayed in the group of 67 alcohol addicts entering a detoxication treatment after a period of an intensive drinking. The same assays were repeated following 1-2 and 6-12 days of the abstinence. Both markers have shown high values in about 80% of patients immediately after the period of heavy drinking. HDL cholesterol concentration was decreasing more rapidly than GGT activity. Both markers may be of a practical value. However, it seems that GGT activity as the less dynamic test is better for detection of heavy drinkers whereas HDL cholesterol assay will be useful for abstinence monitoring in the course of alcohol withdrawal. It shows well short-term fluctuations reflecting abstinence and its relapses. Both assays are simple and inexpensive.