['To objectively compare the electronic radial scanning echoendoscope (ER-ES) with the mechanical radial scanning echoendoscope (MR-ES) in the quality of endoscopic ultrasonography (EUS) images of gastrointestinal tract and pancreaticobiliary lesions.', "Studied were 56 patients: 20 with gastric cancer, 20 with gallbladder lesions, and 16 with intraductal papillary-mucinous neoplasms of the pancreas (IPMN). They were subjected to EUS, half of them using the ER-ES, and the other half using the MR-ES. EUS images thus obtained were evaluated concerning four items in patients with gastric cancer and those with gallbladder lesions, and three items in patients with IPMN. Six endosonographers blindly assessed two EUS images per patient on a visual analogue scale. In each of the three groups of patients, the evaluators' median scores for the ER-ES and MR-ES for each item were compared.", 'The median scores for the ER-ES were significantly higher than those for the MR-ES in all items in patients with gastric cancer and those with IPMN, and in one item in patients with gallbladder lesions.'] Is an electronic radial scanning echoendoscope superior to a mechanical radial scanning echoendoscope in ultrasound image quality for gastrointestinal tract and pancreaticobiliary lesions?