BACKGROUND: The treatment of biliary stricture is crucially important for continuing stable chemotherapy for unresectable biliary carcinoma; however, there is no consensus regarding the use of hilar biliary drainage. In this study, we examined the efficacy of endoscopic over 3-branched biliary drainage using self-expandable metallic stents (SEMSs) in patients with unresectable malignant hilar biliary stricture (HBS). METHODS: A total of 77 patients with unresectable HBS treated with a SEMS and chemotherapy were retrospectively reviewed. There were 59 patients with cholangiocarcinoma and 18 patients with gallbladder carcinoma. The patients were divided into 2 groups (4- or 3-branched group and 2- or 1-branched group) and compared with respect to the duration of stent patency and overall survival. RESULTS: A comparison of the patients' baseline characteristics showed no significant differences between the 4- or 3-branched group and the 2- or 1-branched group. Neither the duration of patency nor survival time exhibited significant differences between the 2 groups, although, among the patients achieving disease control , the duration of patency period and survival time of the 4- or 3-branched group were significantly higher than those observed in the 2- or 1-branched group (P=0.0231 and 0.0466). CONCLUSIONS: The use of endoscopic over 3-branched biliary drainage with a SEMS may improve the duration of patency in patients with HBS.