Alcoholic patients admitted to medical wards (n=63) and to an alcoholism treatment program (n=412), respectively, were differentiated biochemically and hematologically from each other, as well as from a group of nonalcoholic hospitalized controls (n=40). A quadratic multiple discriminant analysis of blood chemistry tests classified 100% of medical ward alcoholics as alcoholic, 94% of treatment program alcoholics, and 100% of medical controls as nonalcoholic. An expanded control group (n=52) containing 12 patients with biopsy-verified nonalcoholic liver disease was compared with a combined group of age-matched medical ward and treatment program alcoholics (n=126). All controls and 86% of the alcoholics were correctly identified. Sixteen of a group of purported nonalcoholics (n=23), whose drinking practices exceeded our criteria for the nonalcoholic sample, were identified as alcoholic. It is concluded that routine chemistries can be used reliably as a clinical adjunct by the physician to identify individuals whose biochemical and hematological profiles are similar to those of documented alcoholics.