We analyzed 40 cases of pancreatic pseudocysts who were treated in Taejeon Eulji General Hospital from Jan. 1986 to Jan. 1994 in retrospective way about their etiology, diagnostic mo- dalities, clinical course and end results of management. Alcohol was the most common etiolog- ic agent(42.5%). Computed Tomography was the most accurate(93.5%) and frequently used diagnostic tool and endoscopic retrograde cholangiopancreatography was very useful in plan- ning surgical treatment. Spontaneous resolution and complications were related to its size sig- nificantly. All cases of diameter under 5 cm were resolved spontaneously and 11 cases(73.3 %) of diameter over 10cm showed complications such as infection, pleural effusion, and asci- tes etc. Percutaneous needle aspiration(2 cases) and internal drainage(20 cases) provided good end results without severe postoperative complications. In conclusion, large sized (diame- ter over 5cm), older than 6 weeks of duration and symptomatic pancreatic pseudocyst is to be best treated by internal drainage. (Korean J Gasfroenterol 1994; 26: 1002 1009)