Doubling times of early and advanced gastric cancers were determined on serial double-contrast roentgenographs, and those of tumor metastatic to the abdominal wall from the stomach were calculated from direct measurement. Doubling times of early gastric cancer ranged from 577 to 3462 days, while advanced gastric cancer had doubling times from 69 to 305 days. Doubling times of tumors metastatic to the abdominal wall were shorter, that is, from 17.7 to 60.2 days. The difference of growth rates in these three situations may result from differences in cell loss in each case. Equally important, the peptic ulceration which accompanies early gastric cancer seemed to have a dual significance; that is, in many cases of early gastric cancer it had an important role as a factor in cell loss, but in some cases it was likely to accelerate to a deeper cancerous invasion. From the retrospective or prospective follow-up study, early gastric cancer, type IIb, was likely to show abnormal redness or discoloration on the mucosal surface, which could be more easily recognized at endoscopy with the dye-spraying method.