Since 1971, when the first draft of the "Group Classification", which classifies the atypism of histological structure in biopsy specimens of the stomach, was proposed by the Japanese Research Society For Gastric Cancer, this classification has come into wide use in Japan. It was, however, revised in 1983, and, according to the revised classification, group III was defined as general histological findings in which it is difficult to make a differentiation between benign and malignant by biopsy specimens. Consequently, the new group III includes, various borderline histologies, in addition to the old group III, which had been defined as the histological features corresponding to those observed in gastric adenoma in biopsy specimens. At the National Cancer Center Hospital, 13,909 gastric biopsies were performed during the period between 1973 and 1982. By retrospective review of these, histological findings in 247 lesions of 231 cases corresponded to group III by the old classification (adenomatous type) and in addition to these, 54 lesions of 54 cases to group III by the new classification (non-adenomatous type). We compared the endoscopic and pathological features between the two types, and the following results were obtained: The false-negative rate of malignancy in the non- adenomatous type (24%) was much higher than that in the adenomatous type (6%). The difference between the two may suggest that, with the adoption of the new group classification, clinical treatment of the patients with group III becomes more complicated due to the increase of the false-negative rate. Endoscopically, most (84%) of the lesions in the adenomatous type were seen as polypoid, while in the non-adenomatous type, depressed lesions were dominant (80%). And, endoscopic details of the polypoid or depressed appearances were mostly different between the two types. These nuances of endoscopic appearance between adenomatous and non-adenomatous types are applicable to decisions regarding, adequate clinical treatment for patients diagnosed as group III by the new "group classification." Good communication between the endoscopist and pathologist is indispensable.