The ideal site of puncture will be determined by the site of maximum bulge on the posterior gastric wall. A needle knife will be used to puncture into the gastric or cyst wall with the help of electrocoagulation. A gush of cyst fluid will be encountered when the cyst is entered. A guide wire will be then passed through the needle knife. A balloon will be used to dilate the opening up to 15 mm without cutting. One 10 Fr plastic double pigtail stent will be placed into the pseudocyst. The stent will be removed three months later. If there is no bulge on endoscopic view, cystogastrostomy will be done under endoscopic ultrasonography guidance.