Histologic discrepancy may sometimes occur between biopsy and endoscopic resection. We investigated the discrepancy rate between the biopsy and the resection lesion in the Korean population. From January 2010 to October 2016, 268 patients with gastric endoscopic mucosal resection/endoscopic submucosal dissection history from nationwide hospitals were enrolled retrospectively. We compared the histologic discrepancy rates from the biopsy and the resection. The mean age was 63.2 years. Gastric adenomas occurred most frequently in the antrum. The pathology of the resected specimens classified 25 lesions (9.3%) as gastritis/hyperplasia, 146 lesions (54.5%) as low-grade dysplasia, 76 lesions (28.4%) as high-grade dysplasia (HGD), and 21 lesions (7.8%) as adenocarcinoma. The discrepancy rate between biopsy and resection was 23.1 per cent. Among the 44 cases of gastritis/hyperplasia, two cases (4.5%) were diagnosed as HGD and 11 cases (25.0%) were diagnosed as cancer after resection. Among the 182 cases of low-grade dysplasia, 33 cases (18.1%) were diagnosed as HGD and nine cases (5.0%) were diagnosed as cancer after resection. Gastritis/hyperplasia, ulceration, and lesions in the lower body location were significant factors related to the discrepancies. Especially, discrepancy occurred most frequently in gastritis/hyperplasia lesions with ulcer in the lower body. There was considerable histologic discrepancy between biopsy and resection. Ulcerative-type tumor morphology and biopsy diagnosis of gastritis/hyperplasia are suggestive factors predictive of discrepancy between biopsy and resection in terms of malignancy. Therefore, although the results of biopsy are gastritis/hyperplasia, suspicious tumorous lesions with ulcer should be indicative of active endoscopic resection for diagnosis and treatment.