Endoscopic ultrasonography (EUS) is a relatively new diagnostic method to assess the extent and the depth of infiltration of esophageal carcinoma. Since October 1990, EUS was performed in 55 patients presenting with squamous-cell carcinoma of the esophagus, 40 of whom were operated on. The first 23 patients underwent EUS with an Olympus GF-2/EU-M2 echoendoscope with a 7.5-MHz transducer; the last 32 patients underwent EUS with an Olympus GF-3/EU-M3 instrument with a 7.5-12-MHz echoprobe. In 22 patients, the procedure was not completed because of the impossibility of passing through the neoplastic stenosis. The depth of infiltration (T parameter) was correctly defined by EUS in 36 of 40 patients (90%) compared with 50% of computed tomography (CT). The 12-MHz echoprobe yielded a global accuracy in staging T parameter of 94% compared to 82% of 7.5-MHz transducer. The lymph-node involvement (N parameter) was correctly classified by EUS in 20 of 23 patients (87%) compared with 39% by CT. EUS provides a high degree of accuracy in assessing the T and the N parameter in the staging of squamous-cell esophageal carcinoma. The major problem of the instrument is still the frequent impossibility of passing through the neoplastic stenosis.