This study was designed to clarify the clinical and pathologic features of diffusely infiltrative squamous cell carcinoma of the esophagus. Diffusely infiltrative squamous cell carcinomas were classified grossly into two types, namely, scirrhous carcinoma and nonscirrhous carcinoma. There were seven patients with the former type and three with the latter type. Scirrhous-type carcinoma was associated with a prominently thickened esophageal wall with strictures, whereas nonscirrhous-type carcinoma demonstrated thickening of the esophageal wall without strictures. Microscopically, all patients had lymph node metastases and lymphatic invasion. Blood vessel invasion was found in seven patients and extranodal invasion was found in seven. The prognosis of patients with both types of carcinoma was extremely poor. Only two patients who underwent curative surgery as well as chemoradiotherapy survived for more than 1 year. Therefore, further morphological studies on the early stages of diffusely infiltrating esophageal carcinoma should be performed. New treatment strategies such as intensive preoperative chemoradiotherapy based on sensitivity tests in individual patients will be required for treating the advanced stages of this disease.