OBJECTIVE: The study examined characteristics associated with substance abuse among patients on a VA general inpatient psychiatry unit. METHODS: A total of 452 consecutive discharge summaries from a six- month period were examined for a recorded diagnosis of psychoactive substance abuse or dependence and evidence of negative social or health effects from the use of drugs or alcohol within one month of admission. The summaries were divided into three groups-no active substance abuse, active alcohol dependence, and two or more active substance dependencies. The demographic, diagnostic, and treatment outcome characteristics of the three groups were compared. RESULTS: Fifty-eight percent of the summaries included evidence of dependence on at least one substance. The three study groups differed in age, gender, racial mix, and psychiatric comorbidity. The group with no active substance abuse had an older mean age, included a higher proportion of women, and had a higher proportion of patients with bipolar disorder (manic), unipolar depression, and dementia. The group with two or more substance dependencies had a younger mean age, a higher proportion of African Americans, and a higher proportion of patients with cluster B personality disorders and schizophrenia. The group with alcohol dependence only was intermediate in age between the other two groups and had a racial mix similar to that of the group with no substance abuse. CONCLUSIONS: A high proportion of veterans seeking mental health care have substance dependencies. The relatively distinct profiles of the patients who abuse alcohol only and those who abuse more than one substance suggest the need for programs specifically tailored to each of these two groups.