A report of an innovative approach to the treatment of locally recurrent rectal cancer following abdominoperineal resection is presented. Curative doses of external beam radiation therapy could not be delivered to an area of locally recurrent cancer because of contiguous small-bowel loops. The patient received 5040 rads external beam radiation therapy, and then underwent intraoperative electron beam boost to the main tumor-bearing area. An additional 1500 rads was delivered with 23 MeV electrons. This approach can be safely applied to selected patients with residual, primarily unresectable, or locally recurrent adenocarcinoma of the rectum or rectosigmoid.