Various kinds of classification have been postulated, however, there remains no plausible classification until now. The Research Society for Gastritis performed a pilot study to establish the ...endoscopic classification under consideration of the factors such as (1) easy-to-use, (2) permitting the common image, (3) presence of pathological evidence. Eight basic endoscopic and histologic patterns of gastritis (superficial, hemorrhagic, erosive, verrucous, atrophic, metaplastic, hyperplastic and special types) were defined, respectively. One hundred and fifty-five patients were enrolled and underwent gastroendoscopy. Presence of 8 items with 13 findings was endoscopically assessed and endoscopic diagnosis of gastritis was made according to the definition of endoscopic types of gastritis More than 5 biopsy specimens were obtained from the lesser and greater curvatures of the antrum and the corpus, and histologic findings of gastritis and Helicobacter pylori infection were assessed. The histologic diagnosis of gastritis was made according to the definition of histologic types of gastritis in a blind fashion for endoscopic diagnosis. Then comparison of the endoscopic diagnosis to the histologic diagnosis was performed. As the results, in diagnosis of erosive, verrucous and atrophic gastritis, the consistency rates between endoscopic and histologic diagnosis were 40 to 86%, and sensitivity, specificity and accuracy were 62 to 98%. Regarding superficial gastritis, the consistency ratio and sesnsitivity in the corpus were 50% and %, but 6% and 8% in the antrum, respectively. Intestinal metaplasia and hyperplastic gastritis were only correctly diagnosed in severe cases. These results suggest that stipulation of 5 basic patterns including superficial, erosive, verrucous, atrophic and special types is reasonable. Exclusion of metaplastic and hyperplastic types from the basic endoscopic classification is appropriate. New definition of gastritis in the antrum accompanied with redness still remains to be investigated.