559 Background: Metachronous recurrence after endoscopic resection (ER) of gastric cancer is known to be high. However, recurrence rate of metachrous lesions after ER of gastric adenoma has not been studied well. The aim of the study was to compare the metachronous recurrence between gastric carcinoma and adenoma patients. Methods: Four hundred eight carcinoma and 539 adenoma patients were enrolled in this study, and median follow-up period was 27 months (IQR: 16-45 months). Clinicopathological characteristics were assessed. At the follow-up endoscopy, the whole gastric mucosa was examined thoroughly to detect any gastric neoplasia. All suspicious lesions were evaluated histologically on endoscopic biopsies. Surveillance endoscopic schedule was as follows: every 3–6 months within 1 year, then once every year. Results: Forty three metachronous recurrence was diagnosed in in carcinoma patients and 45 in adenoma patients. There was no significant difference in the incidence of recurrent metachronous neoplasm between carcinoma and adenoma patients (p=0.728, log-rank test). After excluding metachronous adenoma, cancer recurrence was not different either between two groups (p=0.943). After adjusting for age, sex, multiplicity, and Helicobacter pylori status, the risk of the metachronous development of gastric cancer in adenoma patients was similar with that in carcinoma patients (HR, 0.96; 95% CI, 0.63-1.45). Conclusions: Metachronous gastric cancer after ER of gastric adenoma was as high as that of gastric carcinoma. Similar endoscopic surveillance program should be applied for both gastric carcinoma and adenoma patients after ER.