The authors analyzed the clinical and CT findings in 100 normal subjects and 31 patients with gastric disease to determine the significance of thickening of the gastric wall. Ninety per cent of the normal individuals had a wall thickness less than 1 cm with adequate distension of the lumen. Twenty-nine of the 31 patients with gastric disease (94%) had a wall thickness greater than 1 cm. Adenocarcinoma and lymphoma could not be reliably distinguished based solely on the pattern of gastric wall involvement, although most lymphomas had a lobular luminal contour while advanced adenocarcinomas had flattened inner margins. All 4 leiomyosarcomas were seen as large extragastric masses, and some had calcification or central necrosis. CT was helpful in assessing metastatic spread in 25 patients. While it could not distinguish between neoplastic and inflammatory disease or among histological types of tumor, it was a sensitive detector of gastric disease.