A patient experienced a silent gallstone accompanied by acute severe pancreatitis during interferon theraphy for renal cell carcinoma. Although the gallstone was highly suspected to be the cause of the pancreatits, there were no duodenoscopic or endoscopic retrograde cholangiopancreatographic findings suggesting gallstone pancreatitis such as papillitis, impacted papillary and common bile duct stones, and/or a wider cystic or pancreatic duct, respectively. It is believed that the acute pancreatitis in the presenting case was probably caused by interferon because 1) sludge nor biliary crystal was not detected by light microscopic examination, 2) no tumors, anomalies, nor any obstructing ductal lesions in the pancreas were found, 3) this patient had no other potential causes of acute pancreatitis, and 4) there was no use of potential drugs which could be responsible for the acute pancreatitis other than interferon. In addition, trials of endoscopic drainage of complicated pancreatic abscesses were discussed. (Korean J Gastrointest Endosc 2000;20:77~82)