Background/aims: We aimed to compare the value of endoscopic ultrasonography and magnetic resonance cholangiopancreatography in identifying the patients with mild-moderate acute biliary pancreatitis who require endoscopic retrograde cholangiopancreatography. Material and Methods: The study was prospectively conducted in a tertiary hospital between June 2006 and October 2009. Ninety-five patients without urgent endoscopic retrograde cholangiopancreatography requirement and with mild-moderate acute biliary pancreatitis were included in the study. Patients whose amylase, C-reactive protein, and bilirubin levels had decreased more than 50% on the fifth day compared to admission levels were randomized to magnetic resonance cholangiopancreatography or endoscopic ultrasonography, and the common bile duct was evaluated. Endoscopic retrograde cholangiopancreatography was performed in patients with stone detected with endoscopic ultrasonography or magnetic resonance cholangiopancreatography. With regard to the presence of common bile duct stone in endoscopic retrograde cholangiopancreatography, endoscopic retrograde cholangiopancreatography performances were classified as therapeutic or diagnostic. Results: Endoscopic retrograde cholangiopancreatography was performed in 16 of the 48 patients (33.3%) in the endoscopic ultrasonography group and in 18 of the 47 patients (38%) in the magnetic resonance cholangiopancreatography group. Therapeutic endoscopic retrograde cholangiopancreatography was performed in 14/16 patients (87%) in the endoscopic ultrasonography group and in 16/18 patients (88%) in the magnetic resonance cholangiopancreatography group. The ratio of total number of endoscopic retrograde cholangiopancreatographis was not significantly lower in the endoscopic ultrasonography (16/48) than in the magnetic resonance cholangiopancreatography (18147) group, and the ratio of therapeutic endoscopic retrograde cholangiopancreatographis (14/16) was not higher in the endoscopic ultrasonography group than in the magnetic resonance cholangiopancreatography group (16/18). Conclusions: The necessity of therapeutic endoscopic retrograde cholangiopancreatography was determined with similar efficacy by endoscopic ultrasonography and magnetic resonance cholangiopancreatography in mild-moderate acute biliary pancreatitis.