We studied a series of 39 patients who underwent computed tomography (CT) of the pelvis and abdomen following surgery for adenocarcinoma of the rectum. Based on the CT findings, recurrent rectal carcinoma was classified into one of four stages: Stage I, intraluminal mass without colon wall thickening; Stage II, colon wall thickening (greater than 1 cm) without invasion of adjacent structures; Stage IIIA, thickening of the colon wall with direct invasion of adjacent organs but not the pelvic sidewalls; Stage IIIB, extension of mass to pelvic sidewalls; and Stage IV, distant metastatic disease. All 30 patients with recurrent rectal carcinoma had positive CT scans. Overall accuracy was 95% with 0% false negative and 5% false positive interpretations. Results indicate that CT is an accurate method of detecting and staging recurrent rectal carcinoma and for aiding the selection of appropriate therapy.