The correlation between the growth pattern and peptic ulceration occurring in the cancer lesion was studied in early gastric cancer. Although the superficially spreading type (Super), which grows slowly, showed a high rate of being accompanied by peptic ulceration (74.0%), the deeply penetrating type (Pen), with rapid growth, had a lower such rate (Pen A- expansive type 9.7%; Pen B- infiltrative type 16.1%). Deep ulceration accompanied 32% of the Super cases, 12% of the small mucosal cases and no cases of the Pen type. The Super and small mucosal types located at the intermediate gland area had peptic ulceration more frequently than those at the other areas. The rate of the cases of peptic ulceration of undifferentiated adenocarcinoma was high in the Super and small mucosal types, and that of differentiated adenocarcinoma was 64.0% in the Super and only 33.3% in the small mucosal type. This study clarified that the growth of early gastric cancer was inhibitively influenced by peptic ulceration, which was modified by the localization and histologic type of the carcinoma.