Background: The use of Roux-en-Y gastric bypass (RYGB) for morbid obesity has raised concern that subsequent endoscopic evaluation of the gastric remnant and duodenum is difficult. By gaining percutaneous access to the gastric remnant, however, both gastroduodenoscopy and endoscopic retrograde cholangiopancreatography (ERCP) can be performed easily. This report describes the results of a novel technique for performing "transgastrostomy" gastroduodenoscopy and ERCP. Methods: Six patients with a RYGB for morbid obesity underwent transgastric remnant endoscopic evaluations. If a gastric remnant tube had not been placed during prior surgery, one was placed percutaneously by an interventional radiologist. The tube tract then was dilated to either 20- or 24-Fr. At the time of endoscopy, the gastrostomy tube was removed and the skin anesthetized. Then either a pediatric duodenoseope (outer diameter, 7.5 mm) or a slim gastroscope (outer diameter, 5.9 mm) was inserted through the gastrostomy tube tract. Results: Percutaneous gastroduodenoscopy was successfully performed for all six patients. The findings included two patients with prepyloric ulcers identified and assessed with a biopsy, one patient with intestinal metaplasia and a benign gastric polyp, and three patients with a normal gastric remnant and duodenum. A nonstrictured enteroenterostomy was noted in one of the three patients with a normal endoscopic evaluation. Percutaneous transgastrostomy ERCP was performed for three of the six patients who underwent gastroduodenoscopy. The findings included one patient who had papillary fibrosis treated with a sphincterotomy, a second patient with a normal biliary tree, and a third patient with a normal pancreatic duct. Selective cannulation of the common bile duct was not successful in the third patient. Conclusion: The transgastrostomy endoscopic route ensures access to the excluded stomach and proximal small bowel after RYGB. This route is safe and effective, allowing the use of a duodenoscope to improve the cannulation success rate for ERCPs in this patient population.