SummaryThe social and medical characteristics of 228 ‘mixed’ (drug abusing) and 773 ‘pure’ alcoholics admitted to an inpatient treatment facility were compared. The mixed group, besides being younger, was sociologically more isolated and disaffiliated than was the pure group. As well, the mixed alcoholics were, in general, 'sicker medically than were their non‐drug‐abusing counterparts. The recorded lifetime frequencies of neurological, genitourinary, respiratory and locomotor illnesses were all greater in the mixed compared with the pure group. Trauma and malnutrition were also more common, and among those forty years of age and over the incidences of epilepsy, gastritis, tuberculosis, gonorrhoea, and peptic ulcer were all significantly greater in the mixed group. Cardiovascular illnesses, however, were recorded less frequently in the mixed group, as was cirrhosis among those aged forty and over. Possible reasons for these observations ar