This report combines five-year survival and cause of death in individuals discharged from Washington State mental hospitals with (1) mental illness only, (2) co-occurring mental illness and substance use disorder, or (3) substance use disorder only. Five-year survival was similar in the three groups, although after adjusting for age, individuals with co-occurring disorders or substance use disorder were almost 50% more likely to die than those with mental illness only. Persons with these conditions need treatment to prevent premature death and medical conditions directly related to substance use disorder.