Aims: This study assesses the value of endorectal ultrasound (ERUS)-directed biopsy in detecting local recurrence of rectal cancer. Methods: We reviewed the records of patients undergoing ERUS by a single surgeon for surveillance after treatment of rectal adenocarcinoma. Lesions suggestive of local recurrence underwent ERUS-assisted core-needle biopsy (EAB) via a proctoscope after precise ERUS localization or direct ERUS-guided biopsy (EGB) via a B&K Medical probe. Results: From 1991 to 2003, 525 patients underwent 2,490 surveillance ERUS. Of these patients, 51 underwent 62 biopsy sessions: 36 EGB and 26 EAB. The mean age of patients was 67.2 years (range 38-93 years); 22 (43%) were female. Only 11 patients (22%) had undergone prior radical resection of their primary tumor. No patient experienced a complication from the biopsies despite five being anticoagulated. Of 39 patients whose cancer recurrence was documented during follow-up, 32 (82%) were diagnosed at the initial biopsy session, and in five (13%), recurrence was detected only with ERUS. The combined sensitivity, specificity, and accuracy of EAB and EGB in detecting recurrence was 83, 100, and 87%, respectively. In 26 patients with local recurrence, resection was performed with curative intent. Conclusion: ERUS with biopsy is useful in detecting local recurrence after treatment of rectal cancer. It is safe, with a high diagnostic yield. It may be particularly useful in patients at higher risk for local recurrence (i.e., after endocavitary radiation and local excision) and may allow early detection of local recurrence, thereby permitting attempts at curative resection.