The pathologic features and prognosis of patient in whom gastric cancer simulates at endoscopy as a benign gastric ulcer has been poorly characterized. We performed a retrospective study with particular reference to the long term prognosis on 191 patients treated for gastric adenocarcinoma over the period 1980-1986. In 176 of these 191 patients (92.2%), the endoscopic findings suggested cancers, while in the remaining 15 patients (7.8%), the endoscopic appearance suggested benign ulcer. Comparing gastric cancers masquerading as benign gastric ulcers with those appeared malignant endoscopically, the former had higher resectability rate (100% vs 77.3%), higher incidence of early gastric cancer (73.3% vs 6.25%), less poorly differentiated carcinoma (33.3% vs 65.4%), less lymph node metastasis (13% vs 69.5%) and a higher five-year survival rate (86.6% vs 24.8%) (p less than 0.05 in all). Our study indicated that gastric adenocarcinomas simulated benign gastric ulcers at endoscopy are mostly early gastric cancers that carry a much better prognosis.