AIM: To compare the efficacy of self-expandable metallic stents (EMS) in the treatment of distal and proximal stricture of malignant biliary tumors.METHODS: From March 1995 to June 2004, 61 patients (40 males, 21 females) with malignant biliary obstruction who received self-expandable metallic stent implantation were reviewed retrospectively. The stents were inserted by an endoscopic or percutaneous transhepatic method.We tried to place two stents in the biliary system in T or Y configuration in cases of hilar tumors with bilateral hepatic duct obstruction. The end points of the study were stent occlusion or patient death.RESULTS: The mean time of stent patency was 421 ±67d in the group of proximal stricture( group Ⅰ) and 168 ±18 d in the group of distal stricture (group Ⅱ). The difference was significant in borderline between the two groups (P=0.0567). The mean survival time was 574±76 d in group Ⅰ and 182±25 d in group Ⅱ. There was a significant difference between the two groups (P=0.0005).CONCLUSION: EMS implantation is a feasible, palliative method for unresectable malignant biliary obstruction.The clinical efficacy of EMS in patients with proximal hilar tumors is better than that in patients with distal tumors.