Background: A small portion of patients are diagnosed as early gastric cancer (EGC) and undergo endoscopic submucosal dissection (ESD) at young age, however, their clinical outcomes are rarely known. We investigated clinical characteristics and outcomes of patients who underwent ESD for treatment of EGC at age under 50. Methods: We enrolled patients who were diagnosed as EGC and underwent ESD during 2006 and 2020. We divided them either for young age (YA) group if age ≤ 50 years and other age (OA) group if > 50 years. Results: We enrolled 1,349 patients (YA group: 105 patients [7.8%], OA group: 1244 [92.2%]). Compared with OA group, YA group contained more female patients (36.2 vs. 26.5%, P= 0.033), their tumor was located at middle third (41.0 vs. 29.6%, P= 0.006) and was depressed (40.0 vs. 28.8%, P= 0.001), and had more undifferentiated (30.5 vs. 12.1%, P< 0.001) and diffuse type (22.9 vs. 7.3%, P< 0.001) histology. However, synchronous tumor was less frequent in YA group (2.9 vs. 12.4%, P= 0.001). When we sorted 884 patients who achieved curative resection and were followed-up longer than 12 months, Kaplan-Meier analysis showed that metachronous neoplasm (dysplasia or cancer) and metachronous cancer were significantly less in YA group than OA group (P= 0.003 and 0.013, respectively), however, local recurrence was not significantly different between two groups. Conclusions: ESD is a favorable and effective therapeutic modality for EGC patients who are aged under 50, once curative resection is achieved.