Abstract: Objective:To evaluate the application value of magnetic resonance cholangiopancreatography (MRCP) in diagnosing cholangiectasis.Methods:The data of MRCP imaging and diagnosis of 45 cases with cholangiectasis diagnosed by clinic and operation were retrospectively analyzed.Results:Among 45 cases with cholangiectasis,choledocholithiasis in 24 cases,cholangiocarcinoma in 10 cases(including 7 cases in hepatic portal and 3 cases in common bile duct),gallbladder carcinoma in 2 cases,pancreatic head carcinoma in 2 cases,choledochocyst in 4 cases and cholangitis stenosis in 3 cases were found.The coincidence rate of MRCP in diagnosing the cholangiectasis and stenosis and the causes of cholangiectasis were 100.00% and 93.33% (42/45),respectively.Conclusions:MRCP is a noninvasive diagnostic tool,which has high accuracy in diagnosing the location and cause of bile duct expansion.MRCP should be a routine means for cholangiectasis.