Objective Life expectancy of psychiatric patients is markedly shorter compared to the general population, likely partly due to smoking or misuse of other substances. We investigated prevalence and correlates of substance use among psychiatric patients. Methods Within the Helsinki University Psychiatric Consortium Study, data were collected on substance use (alcohol, smoking, and illicit drugs) among patients with schizophrenia or schizoaffective disorder (n = 113), bipolar (n = 99), or depressive disorder (n = 188).