Purpose: This study was conducted to compare demographic and characteristic differences in self-poisoned patients by age groups using a comprehensive trauma database. Methods: This study included 1,823 patients who were admitted to the emergency room following self-poisoning. Three age groups were defined: young patients (less than 19 years), adult patients (19 to 64 years) and elderly patients (65 years and old). From January 2011 to December 2015, data were obtained from in a single emergency medical center. We investigated the materials of poisoning, ingestion time, GCS, systolic blood pressure, heart rate, and outcomes of patients. Results: A total of 1,823 self-poisoned patients visited the hospital during 5 years. Among these, 130 (7.1%) were categorized as young, 1,460 (80.1%) were adults and 233 (12.8%) were elderly. The most common drug of self-poisoning substances was antipyretics (50.0%) for those in the young group, sedative drugs (45.0%) for adults, and pesticides (41.2%) for the elderly. Mortality was 2.7% in the adult group and 14.6% in the elderly group. After adjusting for all factors related to mortality, the odds ratio (OR) of mortality was 2.63 in the elderly group (95% confidence interval [CI]: 1.44-4.81). Conclusion: There were definite differences in the characteristics of three groups. The younger patients used drugs that could be easily obtained while older patients used more lethal drugs.