Objective: To investigate the clinical significance of magnetic resonance cholangiopancreatography (MRCP) utilizing half-Fourier acquisition single-shot fast spin-echo (HASTE) in the diagnosis of bile duct diseases. Methods: Forty-three patients with obstructive jaundice and 4 without were enrolled in this study. The underlying diseases included bile duct calculi (13 cases), chronic cholangitis (14 cases) malignant tumors (18 cases) and congenital biliary cysts (2 cases). All patients underwent examinations with magnetic resonance imaging (MRI) and MRCP, and 39 were also examined with B-type ultrasonography, 33 with CT and 25 with ERCP and PTC. Three-dimensional image reconstruction was performed using volume-rendered technique (VRE) on the basis of the data obtained by MRCP. Results: The biliary calculi were displayed as circular filling defects in MRCP images, with the proximal end of dilated bile duct taking the form of the mouth of a cup. The bile duct of patients with chronic cholangitis showed distal end dilation and thinner proximal end without discontinuity. Interception of the bile ducts was most frequent (72.2%) in cases of malignant bile duct obstruction, in which the ducts may also be mastoid or resembling rat tails. 72.2% of the cases had severe dilation of the bile ducts, which occur in only 16.0% of the benign cases, with significant difference between them (P<0.01). In images of intrahepatic biliary cyst, intrahepatic duct dilated in the shape of a bursa in connection with the duct. By MRCP, 20 malignant obstructions of the bile ducts were identified with 2 misdiagnoses, and in 25 cases of benign obstructions identified by MRCP, only 1 misdiagnoses occurred. Thus MRCP had the sensitivity, specificity and accuracy of 90.0%, 96.3% and 93.6% respectively in discriminating benign and malignant diseases of the bile ducts, showing a total diagnostic accuracy of 94.0% that was similar to that of ERCP (92.0%) but significantly higher than those of both CT (75.0%) and B-type ultrasonic examination (74.0%). Conclusion: In diagnosing obstructive jaundice, HASTE MRCP is similar to ERCP but better than CT and B-type ultrasonography, with the merits of fast imaging and high resolution as an ideal sequence for MRCP imaging.