Objective: Nonoperative drainage either by the percutaneous or endoscopic route has become a viable alternative to surgical drainage of pancreatic pseudocysts. Endoscopic drainage has been reported in a few small series with encouraging short term results. The aim of this study was to determine the indications, suitability, and long term outcome of transmural endoscopic drainage procedures. Methods: All patients presenting over a 2-yr period to a tertiary referral hepatobiliary unit with pancreatic pseudocysts were studied. Endoscopic drainage was performed in patients with pseudocysts bulging into the stomach or duodenal lumen. Outcome measures were successful drainage of the pseudocyst, complications, and recurrence rates. Results: Of 66 patients presenting with pseudocysts, 34 were considered suitable for endoscopic drainage. Twenty-four (71%) were successfully drained. Failures were associated with thick walled pseudocysts (>1 cm), location in the tail of the pancreas, and pseudocysts associated with acute necrotizing pancreatitis. There were three recurrences (7%), two of which were successfully redrained endoscopically. The long term success rate (median follow-up, 46 months) of the initial procedure was 62%. Conclusion: Transmural endoscopic drainage is a safe procedure with minimal complications. It should be the procedure of choice for pseudocysts associated with chronic pancreatitis or trauma, with a wall thickness of <1 cm and a visible bulge into the gastrointestinal lumen. Forty percent of pseudocysts fulfilled these criteria in our study.