A 47-year-old woman with a history of Roux-en-Y gastric bypass developed a pancreatic pseudocyst after an episode of acute necrotizing pancreatitis. She presented with intractable abdominal pain and weight loss. Computed tomography scan revealed an enlarging pancreatic fluid collection abutting the gastric antrum. The patient underwent exploratory laparotomy, at which a Whipple procedure was aborted due to severe fibrosis and necrosis of her pancreas. Retrograde peroral endoscopic pancreatic pseudocyst drainage was successfully performed through the defunctionalized stomach.