Radiation therapy as an adjuvant to surgery and as primary treatment is increasingly employed for rectal cancer. Radiation may be used as an adjunct to surgery for patients with bulky and/or fixed tumors and for patients at high risk for local recurrence. The technique of intracavitary radiation may be used as the primary treatment. In addition, intraoperative radiation therapy (IORT) has been employed for patients with locally advanced disease. Treatment-related side effects vary in both type and severity and are dependent on the total dose of radiation delivered, the dose fractions, time interval between surgery and radiation, as well as the radiation technique used. An understanding of the rationale for the use of radiation therapy in the treatment of rectal cancer is basic to developing strategies for creative nursing interventions.