The large majority of patients with gallstone pancreatitis have a mild course that is not altered by ERCP and endoscopic sphincterotomy, a more selective use of ERCP might be advisable. This study is designed to evaluate the efficacy of preoperative endoscopic retrograde cholangiopancreatography (ERCP) in patients with mild gallstone pancreatitis and to determine criteria predictive of common bile duct stones (CBDS). Methods: We analyzed the value of serum biochemical tests and findings of ERCP in patients with mild gallstone pancreatitis. Preoperatively, ERCP revealed CBDS in 6 of 47 (12.8%) patients with mild gallstone pancreatitis. Laboratory values on admission did not predict CBDS. Persistent hyperamylasemia and increased serum ALT were associated with CBDS. It is unnecessary to perform preoperative ERCP in patients with mild gallstone pancreatitis who have a normalization of serum amylase and liver function tests.