We analyzed the multivariate relationship between alcohol consumption and gamma-glutamyl-transferase (GGT), mean corpuscular volume (MCV), and tobacco consumption. A group of 995 healthy outpatients (604 men and 391 women, 18 to 76 years old) were systematically examined. Daily alcohol consumption was established after an interview regarding complete dietary habits. Significant correlations have been found between daily alcohol intake and corresponding GGT and MCV values, .35 and .34, respectively, in men and .24 and .21 in women. Multiple regression analyses confirm the superiority of GGt over MCV as a laboratory marker of alcohol intake and show the advantage of using them together. A rough estimation of alcohol consumption is proposed as a first step in mass screening of heavy drinkers.