Introduction Esophagogastroduodenoscopy is the gold standard investigation for upper gastrointestinal disorders. To make the procedure safer and more comfortable, thinner endoscopes for conventional oral or for transnasal intubation have been designed. Several trials have been conducted suggesting greater patient tolerance with the thinner scope. At the same time scope features have improved and are increasingly compatible with the standard endoscope. This prospective, randomised study was conducted to evaluate the cardiopulmonary effects, the patient tolerance, and endoscopist evaluation comparing thin transnasal with conventional transoral endoscopy.