This study aimed to examine the cause-specific excess mortality of psychiatric patients in a general hospital in Korea. Between January 1995 and December 2006, 29 986 patients presented to the outpatient clinic of a general hospital in Seoul, Korea, or were admitted to that hospital for psychiatric disorders. Their cause-specific mortality risk was compared with that of age-matched patients from the general Korean population. The mortality risk of psychiatric patients was 1.6 times higher than that of the general population. Inpatients, younger adults, andpatients with alcohol use disorders or schizophrenia had the highest standardized mortality rates (SMRs). Alcohol use disorder was associated with extremely high SMRs of more than 20 for hematological disease and digestive system disease. Effective preventive measures are required to reduce the excess mortality of psychiatric patients, particularly alcohol-dependent patients and younger patients who have been admitted for general psychiatric care.