The suicide mortality rate and risk factors for suicide completion of patients who presented to an emergency room (ER) for suicide attempt and were discharged without psychiatric admission, patients who presented to an ER for psychiatric problems other than suicide attempt and were discharged without psychiatric admission, psychiatric inpatients admitted for suicide attempt, and psychiatric inpatients admitted for other reasons were examined. The records of 3,897 patients who were treated at a general hospital in Seoul, Korea, from July 2003 to December 2006 were reviewed. Forty-three of the 3,897 subjects died by suicide during the 2.5-year observation period. Compared to the general Korean population, the suicide mortality rate was 82-fold higher for suicide attempt patients, admitted; 54-fold higher for suicide attempt patients, discharged; 21-fold higher for nonsuicidal patients, admitted; and 11-fold higher for nonsuicidal patients, discharged. In all four groups, diagnosis of a depressive disorder and suicide attempt at presentation were each significant independent risk factors for suicide completion. These results highlight the need for suicide prevention strategies for depressed patients who present to the ER or are admitted to a psychiatric ward after a suicide attempt.