The immunohistochemical expression of CEA, CA19-9, and DF3 was studied in 20 normal epithelia, 11 cases of dysplasia, 32 squamous cell carcinomas restricted within the submucosal layer (SM carcinoma), and 42 advanced squamous cell carcinomas of the esophagus. The modes of expression were grouped into three patterns, i.e., negative, focal, and diffuse patterns. No diffuse expression of CEA, CA19-9, or DF3 was found in the normal squamous epithelium and dysplasia. In the carcinomas (32 SM carcinomas and 42 advanced carcinomas) the diffuse expression of CEA and CA19-9 was found in four lesions, and only one of the four lesions was an SM carcinoma, while the diffuse expression of DF3 was found in 16 of the 32 SM carcinomas and 25 of the 42 advanced carcinomas. These results indicated that the diffuse expression of these tumor-associated antigens were characteristic of tumor tissue in the esophagus, and particularly DF3 was diffusely expressed earlier than CEA or CA19-9. The expression of DF3 in the esophagus may, therefore, be a marker of the early stage of tumor growth.