Background: Suicide among the elderly is a public health concern, as life expectancy is increasing rapidly and suicide rates increase with age. In Korea, self-poisoning is the most common method of attempted suicide. This study aimed to evaluate the characteristics of attempted suicide by self-poisoning among the elderly and to identify risk factors related to the suicide attempts. Methods: A cross-sectional observational study was conducted using the Emergency Department-based Injury In-depth Surveillance database in Korea. We included all adult patients visiting the emergency department (ED) who attempted suicide by poisoning between January 2011 and December 2017 and stratified according to age: the elderly (≥ 65 years old) and the younger group. Characteristics and risk factors for attempted suicide by poisoning among the elderly were evaluated using stepwise regression analysis. Results: Among 25,904 adult patients, 5,164 (19.9%) were classified as elderly. The elderly were more likely to be admitted to hospital and intensive care units, the average ED length of stay was longer, and total mortality was higher than that of the younger group. Male sex, low socioeconomic status, poor physical health, pesticide use, lower alcohol consumption, and fewer prior suicide attempts were found to be risk factors for suicide among the elderly. Conclusion: Self-poisoning among the elderly is associated with poorer clinical outcomes than in younger adult patients. Suicide among the elderly is a potentially preventable public health problem, and with proper identification of the associated risk factors, appropriate multidisciplinary intervention strategies can be implemented.