Suicidal behavior is a relatively common and serious problem in those with alcohol and drug problems. We compared demographic and clinical characteristics of 123 alcohol rehabilitation patients with and without a history of suicide attempts, using the Schedule for Affective Disorders and Schizophrenia-Lifetime version. Younger age was significantly related to suicide attempts, as were drug disorders, panic attacks, antisocial symptoms, and alcohol-related problems such as violence, withdrawal symptoms, and personal or occupational loss. Untreated suicide attempts were characterized by less serious suicidal intent and medical threat to life. However, alcohol-or drug-abusing individuals who have not sought treatment for suicidal behavior but who continue to drink or use drugs may be at special risk for completed suicide.