Ten laryngopharyngectomy specimens were dissected to determine the relative accuracy of computed tomography (CT) and endoscopy under anesthesia for evaluating the inferior extent of pyriform sinus carcinoma. Endoscopic examination failed to detect involvement of the pyriform sinus apex in one patient, and considerably underestimated disease at this level in two others; CT accurately predicted the status of the apex in these three and all other patients. Endoscopy underestimated the inferior extent of tumor in six patients; CT revealed the inferior limit relative to the esophageal verge more accurately in all six of these submucosal extensions. Endoscopy revealed one case of mucosal spread to the esophageal verge not demonstrated by CT. Endoscopy and CT were both correct in revealing the esophageal verge to be involved (one case) and free of disease (two cases). This study also confirmed a common tendency of pyriform fossa cancer to spread through thyrohyoid membrane adjacent to the course of superior laryngeal neurovascular bundle (six cases). High-resolution CT, in experienced hands, is a useful adjunct to endoscopy for detecting submucosal, inferior extension of pyriform sinus carcinoma. This information can influence the choice of the lower margin of resection and method of pharyngeal reconstruction.