Patients with head and neck cancer frequently develop synchronous or metachronous esophageal malignancies. Previous studies have demonstrated the efficacy of endoscopic screening for esophageal cancer in head and neck cancer patients. The Narrow Band Imaging (NBI) system, an optical technology that enhances the visualization of superficial vascular network, may be superior to the conventional white light endoscopy for the detection of neoplastic lesions. However, whether the application of NBI improves the detection results have not been critically evaluated.