A case is reported of a 33-year-old man with hepatocellular carcinoma associated with familial polyposis of the colon. During subtotal colectomy for diffuse colonic polyposis, a small tumor was excised from the right lobe of the liver. Histologic examination revealed hepatocellular carcinoma. The association of primary hepatoma in familial polyposis of the colon is very rare. However, it is well known that familial polyposis of the colon has a potent oncogenicity not only in the colon but also in the extracolonic organs. The hepatoma may also be one of the extracolonic malignant manifestations in this inherited disease.