Magnetic resonance imaging of the biliary and pancreatic ducts, MRCP, is a technique developed over the last few years. Using strongly T2-weighted sequences, images of the biliary and pancreatic ducts similar to ERCP can be obtained within one single inhalation. No contrast media or medication is required. In 23 patients 25 MRCP examinations were retrospectively compared with ERCP or PTC. One patient had normal findings; three had gallbladder stones. Eight out of nine common bile-duct stones were shown. MRCP after papillotomy in one patient showed a common bile-duct stone; ERCP seven days later was normal. MRCP correctly showed obstruction and dilatation of the bileducts in ten patients with tumor and in one patient with chronic pancreatitis. Two of these were erroneously interpreted as caused by stone. 21 of 25 MRCPs were consistent with the final diagnosis. We consider MRCP a promising method which may replace diagnostic ERCP in majority of patients. Stones in the gallbladder and bile-ducts can be diagnosed. The method also shows obstructions and other lesions affecting pancreatobiliary ducts.