The elderly population has recently increased, and the need for cancer care and treatment for the elderly is likely to grow. We report on radiation therapy for cancer in elderly patients over 80 years of age. During the period from 1985 to 1996, 90 elderly patients (54 men, 36 women) aged over 80 years were treated with radiation therapy. Many patients had primary tumors of the esophagus, head and neck, and lungs, in that order of frequency. Fifty-seven percent of the patients were treated with radical radiotherapy, and 70% were treated with radiotherapy alone. The rate of completion of radiation therapy was 90%, and the response rate was 82%. Radiation therapy played an important role in the treatment of the patients over 80 years of age. The half of our patients had concurrent medical problems, and were dependent on their home physicians both before and after radiation therapy. We consider that radiation oncologists should make an effort to form a good relationship with home physicians.