OBJECTIVE We evaluated the effectiveness of CT in detecting the recurrence of rectal cancer. METHODS As part of a postoperative follow-up protocol, periodic CT examinations were performed on 67 patients who had had potentially curative surgery for rectal carcinoma. Retrospectively we evaluated the CT of these patients. In 21 patients there was local tumoral recurrence, which was detected by CT in 15. We classified the patients into two groups according to the surgical technique employed: anterior resection (AR) or abdominoperineal resection (APR). RESULTS The sensitivity of CT for the diagnosis of local recurrence was greater in patients with APR (12/13; S = 92%) than in those with AR (3/8; S = 37%). In each group there was one false-positive result--thus both groups showed a similar specificity (94% in APR and 96% in AR). In the APR group, 38% of the recurrences (5/13) were detected initially by CT. Computed tomography was not the first diagnostic test in any of the recurrences after AR. CONCLUSIONS On the basis of these results, we think that CT is a good diagnostic test for local recurrence in patients with rectal cancer and APR.