Endoscopic mucosal resection (EMR) is a recently introduced therapeutic method based on the principles of the strip biopsy for resection of flat lesions of the gastrointestinal tract. Eleven asymptomatic patients (nine men, two women) with superficial carcinoma or high-grade dysplasia of the intrathoracic esophagus were treated by EMR during a 6-month period. The patients' mean age was 64 years (range, 49-78). The site of the lesions was the middle third of the esophagus in eight, upper third in two, and lower third in one patient. All patients in this series had a flat (II) type of superficial cancer. The procedure was carried out in all 11 patients without complication. Histopathological examination of the specimens revealed squamous cell carcinoma in nine patients. The remaining two patients were confirmed to have dysplasia only. Free margins measured greater than 5 mm in all cases. No recurrence was detected in a mean follow-up of 8 (5-10) months. For superficial flat lesions, EMR proved to be a safe and curative procedure that provided good quality of life following resection. However, larger trials are needed to confirm these results. Applying EMR to esophageal dysplasia could decrease the incidence of esophageal cancer.