Fifty gastric carcinoma lesions were classified into three groups depending on their morphologic characteristics on incremental dynamic computed tomography (CT). Two-layered tumors (23 cases) showed both an outer layer of low attenuation and a thick inner layer of high attenuation. Furthermore, they were classified into two subgroups depending on the thickness of the outer layer. Two-layered tumors showing a thick outer layer (13 cases) were all scirrhous carcinomas. The mean thickness was 11.05 +/- 3.38 mm for the outer layer, and 4.40 +/- 1.92 mm for the inner layer. The thick outer layer corresponded histopathologically to the layer submucosal to the serosa, and the thick inner layer, to the mucosal layer. Two-layered tumors showing the thin outer layer (10 cases) were all non-scirrhous carcinomas. The mean thickness was 1.62 +/- 0.47 mm for the outer layer, and 12.34 +/- 8.68 mm for the inner layer. Tumors of high attenuation (12 cases) and tumors of low attenuation (15 cases) were also nonscirrhous carcinomas. In conclusion, all scirrhous carcinomas showed both a thick outer layer and a thick inner layer, whereas non-scirrhous carcinomas did not have appearance. This new classification can serve as a guideline for predicting scirrhous carcinoma on the basis of CT findings.