Objective: It is unknown whether epidemiological or clinical characteristics of Henoch-Schönlein purpura (HSP) have changed over time. This study aimed at evaluating the epidemiological and clinical changes of HSP during 3 decades. Methods: We retrospectively analyzed the data of 515 children with HSP (0-15 years of age) between 1987 and 2015. We compared the two HSP patient groups: those admitted from 1987 to 1996 (group A, 238 cases) and those admitted from 2006 to 2015 (group B, 98 cases), apart a decade. Results: In total 515 patients, the mean age was 6.5 ± 3.0 years and the male-to-female ratio was 1.2:1 (278:237). The age distribution showed a peak at age 5 with a bell-shaped distribution pattern. The annual number of cases varied in each year with a trend of reduced cases in the recent decade. There were less cases during the summer season. Purpura, gastrointestinal involvement, joint involvement, and renal involvement were found in 100%, 56%, 38%, and 18% of the patients, respectively. In comparison between the two groups, there were similar findings in mean age, age distribution, and seasonal distribution. However, the hospitalization stay was longer, and the proportion of recurrent cases (14 cases vs. 0 case) and proteinuria (15% vs. 3%) were higher in the group A than in the group B. Conclusions: Long-term epidemiologic features of HSP were similar to those in other countries. Clinical manifestations of HSP showed a trend towards a less severe clinical phenotype over time in Deajeon, Korea. Key Points. It is unknown whether epidemiological and clinical traits of Henoch-Schönlein purpura (HSP) have changed over time. We reported that clinical manifestations of HSP have changed to milder phenotype through a long-term observation of three decades at a single hospital in Daejeon, South Korea. Clinical phenotype of infection-related diseases, including HSP, may be changed over time, and the etiology and the reason of clinical changes over time remain to be solved.