Fourteen patients who had undergone local excision, anterior resection or low anterior resection for rectal carcinoma were examined by endoscopic ultrasonography. In two of three cases of local recurrent carcinomas, endoscopic sonography was superior to computed tomography in determining the depth of tumor infiltration. There were difficulties in differentiating scar tissue from local tumor formation when the mucosa appeared normal upon endoscopic examination. Only repeated follow-up examinations starting in the postoperative period, will allow a differentiation between scar tissue and local tumor recurrence.