A 34-year-old male who showed a rectal mass upon irrigoradioscopy was admitted on October 6, 1979. Abdominoperineal amputation of the rectum was performed on October 11. Histopathological examination revealed that the tumor was adenocarcinoma of the well differentiated type, s, n0., stage II. The patient received chemotherapy and immunotherapy for 10 months postoperatively. In September 1981, enlargement of the thyroid gland associated with pain was noted and on January 12, 1982 total thyroidectomy was performed. Histologically, a diagnosis of well-differentiated adenocarcinoma, which was a metastasis from the rectal cancer, was made. On August 15, 1982, the patient died of generalized metastases.