Gastric epithelial neoplasia is a very common disease entity in Korea, encompassing gastric adenoma and adenocarcinoma. There are still discrepancies in pathologic diagnosis of gastric epithelial neoplasia between Western and Japanese pathologists after Vienna consensus classification. With increasing use of endoscopic therapy such as endoscopic mucosal resection and endoscopic submucosal dissection, it is very important to agree on the consensus criteria in the diagnosis of gastric epithelial neoplasia among pathologists in Korea. On this background, the current concepts, and contemporary issues of definition, diagnostic and classification criteria of gastric epithelial neoplasia were reviewed.