From April 1989 to June 1991 63 patients with esophageal cancer were investigated by endosonography with the object of ascertaining the depth of intrathoracic tumor infiltration and lymphnode involvement. The sensitivity in diagnosing tumor infiltration amount to 0.74; the sensitivity for involvement of regional lymphnode was 0.84, specificity 0.44. In an in-vitro analysis endosonographic criteria for the assessment of regional lymphnodes are proved. Echogenic structure seems not to be a valuable criterium.