The epidemiology of immune thrombocytopenia (ITP) is not well characterized in an Asian population. From July 2010 to June 2014, ITP patients were identified using the Korean Health Insurance Review and Assessment Service database. The overall incidence rate of ITP was 5.3 per 100,000 person-years (95% CI: 5.1-5.5). The overall incidence rate ratios of children under 15years old to adults and females to males were 3.8 (95% CI: 3.7-3.9) and 1.3 (95% CI: 1.2-1.4), respectively. Of the total 10,814 patients, 3388 patients (31%) needed treatment for ITP; of these, 54% continued treatment for more than three months. First-line therapy consisted of corticosteroids (CS) in 42%, immunoglobulin (IVIg) in 35%, CS with IVIg in 19%, and other immunosuppressive agents (ISA) in 4%. Among treated patients, 75% of adults and 33% of children continued treatment for more than three months. After three months, the most frequently used drug was CS alone in 63% of patients. Only 104 patients underwent splenectomy; of these, 51% received salvage treatment after a median of one month after surgery (range: 0-27). The proportion of patients who received platelet transfusions of 12units or more per month for at least two consecutive months was significantly higher among patients treated for more than three months compared with patients who completed treatment within three months. This population-based study is the first to describe the incidence of ITP and its treatment reality for patients in Korea. Copyright © 2017 Elsevier Ltd. All rights reserved.