Although emergency room psychiatrists are often faced with evaluating and planning treatment for patients who abuse substances, there is limited information about the characteristics of emergency room patients with alcohol- or drug-induced disorders. The authors describe the demographic and clinical characteristics of 343 consecutive patients referred to a general hospital's emergency psychiatry service. The 114 patients diagnosed as having an alcohol- or drug-induced disorder were younger and were more often male, unemployed, and homeless than patients with disorders not induced by substance abuse. They also demonstrated increased suicidality. Alcohol was the predominant substance that contributed to psychiatric emergencies, but a surprising number of patients were diagnosed as having amphetamine-induced disorders, possibly representing an important trend.