An analysis of 17,212 lesions from 15,933 patients with early gastric cancer collected from 110 major hospitals and institutes in Japan is presented.The percentage of patients with early gastric cancer was high among persons in their 60s and 50s. The sex ratio (F/M) was 0.5 but it was higher for younger people than for old people. Regarding distribution of the types of early gastric cancer, the depressed group (Types IIe, III) accounted for 73.9% and the elevated group (Types I, IIa) accounted for 15.3%.The elevated group was more frequent in the older age group. In regard to the type and invasion, slight invasion was prominent in types lIb and IIa, while deep invasion was prominent in IIa + IIc. The metastatic rate was 18.4% for IIa + IIc, 11.8% for I and 11% for IIe. The frequency of lymph node metastasis was +4% in intramucosal cancer, 18.9% in submucosal cancer and 11.4% in total. The type in which multiple cancers were most frequent was lIb, followed by IIa.The percentage of differentiated adenocarcinoma was 91.9% in the elevated group and was found more often among the aged.Undifferentiated adenocarcinoma occurred more often among the young. The relationship between site and histology, location and invasion, location and lymph node metastasis etc. were also investigated. We believe that these results should be very useful for detection and treatment of early gastric cancer.The rate of detection of small cancer is increasing year by year. This increase can be explained by the progress and widespread application of endo-scopy, which will continue to play a large role in diagnosis and treatment of gastric cancer.