In view of uncertainty regarding the criteria and significance of gastric dysplasia as a precancerous lesion, members of the Pathology Panel of the International Study Group on Gastric Cancer (ISGGC) reviewed microslides of 93 gastric lesions showing varying degrees of mucosal abnormality, and reached the following consensus: (1) immature and proliferating gastric epithelium can be divided into two categories: hyperplastic and dysplastic; (2) the term dysplasia, especially of high-grade type, should be restricted to precancerous lesions, and hyperplasia is applied to regenerative changes; (3) regenerative hyperplasia may be simple or atypical, but dysplasia includes both moderate and severe abnormalities, since they often coexist and can not be sharply separated; and (4) occasionally the possibility of malignancy can not be excluded in a severely dysplastic epithelium; in such a case rebiopsy and diligent follow-up are necessary to establish the diagnosis. Criteria for diagnosing dysplasia and hyperplasia are presented and discussed. The opinions are offered as guidelines for establishing the diagnosis of gastric dysplasia and for prospective studies.