A 60 year-old man had giant thickening of the gastric mucosa and mild hypoproteinemia. Chronic abdominal discomfort and suspicious carcinomatous lesion on Upper G.Ⅰ. series and gastroscopic findings eventually required subtotal gastrectomy. Histologically the stomach showed marked thickening of the gastric mucosa with frequent cystic dilatations, especially in the basal layers, some of them herniated through muscularis mucosa, resembling Rokitansky-Aschoff sinus in chronic cholecystitis.