An endoscopy of the stomach with concomitant use of arterial infusion of dye was designed and clinically tried. After arterial infusion of a dye, excavated carcinoma of the stomach was detected as a relatively irregularly stained area with longer retention of the dye as compared with normal area of the stomach. However, the area where carcinoma invaded deeper layers of the gastric wall was not stained. Accordingly, this method is considered useful for estimation of extensiveness and depth of carcinomatous invasion in the gastric wall. Staining of the gastric wall affected by diffuse carcinoma after arterial infusion of dye was poor and irregular. In the case of reticulum cell sarcoma of the stomach, the lesion was not stained at all. Resected stomach with leiomyoma was found to be homogeneously and deeply stained in the tumorous area. This method may be also used for differential diagnosis of nonepitheliar tumor of the stomach and for judgment of intractability of benign gastric ulcer.