The results of endosonography and computed tomography--using an optimized technique of CT--in preoperative staging of esophageal cancer are compared. In 22 of 40 patients with esophageal tumors a complete passage by the ultrasonic endoscope was possible. Endosonography was superior to CT in the assessment of early stages of esophageal tumors (T1/T2). Out of nine tumors confined to the esophageal wall, eight were classified correctly by endosonography, only five by computed tomography. The results in T3- and T4-carcinomas (13 patients) were comparable for endosonography and computed tomography. Endosonography is of importance in the selection of patients with early stages of cancer, in whom a curative resectability is still possible.