To investigate the possibility of whether a single 300 mg dose of ranitidine given orally 2-3h before magnetic resonance cholangiopancreatography (MRCP) could reduce the signal from the stomach and duodenum, and thus increase the conspicuousness of the biliary tree. Thirty-five volunteers (22 female, 13 male), (age range 21-50) were underwent MRCP in a double-blind, placebo-controlled, randomized, crossover trial on a Philips Intera 1.5 T machine using a phased array surface coil. Imaging was carried out in the coronal oblique plane. Six 40 mm sections were acquired at varying angles to delineate the biliary tree and pancreatic duct. The 70 examinations were blindly scored by three consultants experienced in cholangiography. After ranitidine administration there was a significant decrease in signal from the stomach (mean=17.7, p=0.0005, CI 10, 25.3) and duodenum (mean=18.4, p=0.0005, 95%CI 9.6, 27.1) with a significant increase in conspicuousness of the distal common duct (mean=7.7, p=0.033, 95%CI 0.7, 14.7) and proximal common duct (mean=8.7, p=0.010 CI 2.2, 15.2). There were no adverse effects. Oral ranitidine is a cheap and effective agent to decrease signal from the upper gastrointestinal tract and to improve visibility of the biliary tree.