Radiation therapy is commonly utilized as a major component in the treatment of pelvic malignancy. Unfortunately, secondary toxicity to the lower gastrointestinal tract can occur. This most commonly affects the rectum, although injuries to the colon and small intestine are not uncommon. The presentation can be acute or chronic, and different mechanisms are responsible for each. Symptomatology is quite variable but can result in significant compromise for the patient. Numerous preventive and treatment strategies have been applied to this disease process. This article presents a summary of the current knowledge regarding radiation injury to the lower gastrointestinal tract with special emphasis on treatment options for radiation proctitis. Copyright © 2007 by Thieme Medical Publishers, Inc.