Generally, patients with advanced rectal cancer in whom surgical treatment is contraindicated receive radiation or chemotherapy. In such patients, we have administered local injection of methotrexate and mitomycin C bound to activated carbon particles. Four patients received intratumoral injection of the dosage formulation (total dose 100-400 mg of methotrexate or 8-32 mg of mitomycin C) under colonofiberscope. After the treatment, bleeding and pain were lessened in all 4 patients. In two patients, the tumor markedly decreased in size and there was no regrowth prior to death 12-14 months after the treatment. In another patient, bleeding and pain disappeared until the patient died of pulmonary and liver metastases. The fourth patient is alive without regrowth 5 months after treatment. Side effects were not severe.