['Roux-en-Y gastric bypass (RYGB) is a common intervention for morbid obesity. Upper gastrointestinal (UGI) symptoms are frequent and difficult to interpret following RYGB. The aim of our study was to examine the role of endoscopy in evaluating UGI symptoms after RYGB and to assess the safety and efficacy of endoscopic therapy.', 'Between 1998 and 2005, a total of 1,079 patients underwent RYGB for clinically severe obesity and were followed prospectively. Patients with UGI symptoms after RYGB who were referred for endoscopy were studied.', 'Of 1,079 patients, 76 (7%) who underwent RYGB were referred for endoscopy to evaluate UGI symptoms. Endoscopic findings included normal surgical anatomy (n=24, 31.6%), anastomotic stricture (n=40, 52.6%), marginal ulcer (n=12, 15.8%), unraveled nonabsorbable sutures causing functional obstruction (n=3, 4%) and gastrogastric fistula (n=2, 2.6%). Patients with abnormal findings on endoscopy presented with UGI symptoms at a mean of 110.7 days from their RYGB, which was significantly shorter than the time of 347.5 days for patients with normal endoscopy (P<0.001). A total of 40 patients with anastomotic strictures underwent 86 endoscopic balloon dilations before complete symptomatic relief. In one patient, a needle knife was used to open a completely obstructed anastomotic stricture. Unraveled, nonabsorbable suture material was successfully removed using endoscopic scissors in three patients.'] Is endoscopy accurate , safe , and effective in the assessment and management of complications following gastric bypass surgery?