A 79-year-old man was admitted for advanced transverse colon cancer with large bowel obstruction. Twelve years earlier he underwent a total gastrectomy with Roux-en Y reconstruction for gastric cancer. No metastasis was detected preoperatively. Exploratory laparotomy revealed massive direct invasion of the mesenterium of the jejunum for Roux-en Y reconstruction. The primary lesion was unresected and transverse colostomy was made. Systemic chemotherapy with 5-fluorouracil and l-leucovorin was scheduled for a total of 4 courses postoperatively. After completion of this chemotherapeutic regimen, a CT scan and colonofiberscopy revealed the primary lesions had disappeared, and a histological examination of biopsy confirmed that the patient had achieved a complete remission (CR). There was no severe side effect during chemotherapy. The patient is presently enjoying a good general condition and has been free from any sign of recurrence.