We present a new device allowing for the diagnosis and treatment of extended superficial lesions of the esophagus and hypopharynx such as early squamous cell carcinoma, intestinal metaplasia with high grade intraepithelial neoplasia or early adenocarcinoma arising in Barrett's esophagus. A new modified rigid esophagoscope (Karl Storz GmbH, Germany) has been designed. A large mucosal area is sucked against a transparent and perforated hemi-cylindrical window. Mucosal resection is performed by an electrical wire loop at a constant depth of 1 +/- 0.1 mm. The resected surface varies from 4 to 12 cm(2). Circumferential resection consists of two opposite individual hemi-circumferential resections. We performed three series of animal trials: hemicircumferential mucosectomies; circumferential resections of variable (2 to 6 cm) length and long-segment mucosectomies with follow-up. Hemi- and circumferential resections could be done in one or two specimens only which allowed precise histological studies. This facilitated easy orientation and analysis of the surgical margins. The deep resection margin was precisely located at the submucosal level, a prerequisite for a safe resection of superficial cancers of the esophagus and hypopharynx.