Pancreatic pseudocyst occurs as a complication of pancreatitis or trauma, which results in the escape of pancreatic enzymes from the parenchyma or ductal system of pancreas. At that time, serum amylase may have returned to normal level, and the patient may be subjectively asymptomatic. In this phase, the radiologic findings are relatively greater significance than laboratory data. In the conventional radiologic study, pancreatic pseudocyst have been frequently confused with other retroperitoneal mass, but recently with clinical application of ultrasound and CT scan, more accurate diagnosis can be obtained. The brief results are as follows: 1. Male to female ratio was 3:2 in 15 patients. Incidence was most common in young adult age. Most frequent symptom was epigastric pain, and which was noted in 11 cases of patients. 7 cases of patients had past history of abdominal trauma and past history of pancreatitis was only in 1 case. Most common laboratory finding was leukocytosis in 8 cases of patients and elevated serum amylase was also noted in 7 cases. 2. In each 5 cases of patients, plain chest roentgenologic evidence of left side pleural effusion and hemidiaphragm elevation were observed. 3. On flat abdomen film, soft mass shadow was visualized in 8 cases of patients. On UGI series, evidence of retrogastric space widening was observed in 11 cases of patients. 4. The location of pseudocyst is mainly in body and tail of pancrease in 11 cases of patients. 5. More accureable diagnosis can be obtained through application of ultrasound and CT scan.