We analyzed Computed Tomography results of 36 patients with known gastric tumors. The CT scan was taken after each patient had ingested 1000cc of N2 saline or barley tea. Thirty-three patients were analyzed preoperatively. There patients were excluded due to incomplete gastric distension. All the cases were adenocarcinomas. Thickening of gastric wall was detected in all cases. Tumoral ulceration was only diagnosed in 5 of the 25 proven ulcerated tumors. Among the 19 cases which underwent surgery, perigastric fat infiltration(n=15), lymph node metasis(n=9), pancreatic invasion(n=19) were correctly predicted. Acceptance and tolerance of water as a gastric contrast medium was good in all patients and no side effects occured. Water was found to be an excellent negative contrast agent of the gastric wall.