The drinking habits of 55 adolescents, aged 12-22 yr, were evaluated in light of the current presumed upsurge in adolescent alcohol use. SGPT [serum glutamic pyruvic transaminase], SGOT [serum glutamic oxalo acetic transaminase] and alkaline phosphatase concentrations were essentially normal in all subjects. Serum .gamma.-glutamyl transpeptidase (GGTP) concentrations were elevated in 12 of 15 adolescents who consumed 6 or more drinks per day. This test may warrant inclusion among other targeted screening procedures performed in teenage patients suspected of heavy alcohol consumption.