Purpose: The purpose of this study was to investigate the epidemiologic characteristics of patients who visited emergency departments (EDs) after intentional poisoning in Korea. Methods: This study retrospectively analyzed the data of of 23 hospitals during a five-year period, between 2011 and 2015. We included patients who inflicted injury to themselves - attempt of suicide - by means of poisoning. Results: A total of 18,121 patients visited an ED after intentional poisoning. Among them, 58.3% were females; however, there were more males among those aged 60 years or older. The mortality rate for males was 8.6%, which was 3.1 times higher than that for females with 2.8%. The most common poison was pesticides (35.4%) in males and sedative-hypnotics (44.0%) in females. The most common causative agent of death was pesticide in both sexes (75.2% and 65.3%, respectively). Since the production of paraquat was discontinued in 2011, the number of deaths from pesticide poisoning has decreased. The mortality rate declined in both males and females, from 12.6% and 4.5% in 2011 to 7.1% and 2.1% in 2015, respectively. Conclusion: In this study, we analyzed the epidemiologic characteristics of intentional poisoning, especially the frequency of suicide attempts by gender and age group, the cause of suicide, and the causative agent. This can be used as basic data for establishing policies to reduce and prevent suicide attempts by poisoning.