PURPOSE:We describe a rare case of an alpha‐fetoprotein‐producing carcinoma originating in the transverse colon of a 59‐year‐old Japanese male.METHODS:The patient reported an abdominal mass and weight loss. On examination, a tumor of the transverse colon and multiple masses in the liver were found. The serum alpha‐fetoprotein level was extremely high (12,873 ng/ml). The patient underwent right hemicolectomy and intraoperative biopsy of a liver mass.RESULTS:Histologically, the colon cancer was composed of three different components: a well‐differentiated tubular adenocarcinoma, a tubulopapillary carcinoma consisting of cells with clear cytoplasms, and a “hepatoid carcinoma.” The hepatoid carcinoma was composed of large polygonal cells with abundant eosinophilic or clear cytoplasms, arranged in a trabecular or solid pattern, and showing marked vascular invasion. Immunohistochemically, alpha‐fetoprotein was strongly expressed, largely in the hepatoid carcinoma and partially in the tubulopapillary carcinoma. The liver biopsy specimen showed morphologic and immunohistochemical features similar to those of the hepatoid carcinoma of the colon and was therefore diagnosed as a metastasis. The patient died of the cancer two months after surgery.CONCLUSION:Based on our experience of this patient and a review of the literature, alpha‐fetoprotein‐producing colorectal carcinomas are generally associated with a poor prognosis because of the frequent occurrence of blood‐borne metastases.