PURPOSE: MR cholangiography(MRC) in patients with obstructive biliary diseases was evaluated in order to compare its role with that of ERCP or PTC. MATERIALS AND METHODS: Twenty consecutive patients with obstructive biliary and peribiliary diseases (Eleven biliary and peribiliary carcinomas, seven intrahepatic stone diseases and seven extrahepatic stone diseases) were included and ERCP(16 ccases) or PTC(four cases) was performed in all twenty cases. Non-breasth-hold, heavily T2-weighted, fast spin echo MRC was carried out and 2-D axial, coronal images and 3-D images with maximum intensity projection protocol were obtained. We regarded ERCP or PTC as thegold standard and then comparedn MRC with ERCP of PTC retrospectively. RESULTS: In 11 patients with biliary and peribiliary carcinomas, the level of obstruction was depicted in nine cases(83%) on MRC and in six of seven cases(86%) on ERCP. The causes of obstruction were demonstrated in eight cases(73%) on MRC and in six of seven cases(86%) on ERCP. On MRC, Seven cases(64%) revealed similar findings to ERCP or PTC. Of seven cases of EHD and seven of IHD stone diseases, EHD stones were detected in six cases(86%) on MRC and in seven cases (100%) on ERCP,IHD stones were detected in four cases(57%) on MRC and in five cases(71%) on ERCP. 2D-MRC was superior to 3D-MRCin the detection of stones. The extent and grade of ductal dilatiation was accurately revealed in six cases(86%)on MRC and in seven cases(100%) on ERCP of EHD stones, in six cases(86%) on MRC and in three cases(43%) on ERCP of IHD stones. Six cases(86%) of EHD stones and two cases(29%) of IHD stones revealed similar findings between MRCand ERCP. CONCLUSION: MRC findings were similar to those of ERCP or PTC in the evaluation of malignant biliary diseases or extrahepatic stone diseases and was valuable in their diagnoses. In the evaluation of intrahepaticstone diseases, MRC demonstrated dilated peripheral IHDs with stones more difinitely than ERCP but in the detection its accuracy was low. Further studies may therefore be needed.