BACKGROUND: In view of the recent advancement in endoscopic devices for biliary endoscopic intervention, the expert endoscopist can address complex morbidity. However, endoscopic 3-branched partial stent-in-stent deployment of metallic stents (MS) in patients with malignant hilar biliary stricture is technically demanding. OBJECTIVES: To evaluate the efficacy and safety of endoscopic 3-branched partial stent-in-stent deployment of MS. DESIGN: Case study. SETTING: Gastroenterological Center, Okayama University Hospital. PATIENTS: Nine consecutive patients (mean age 63 years, range 52-84 years, mean follow-up period 5 months) with malignant hilar biliary stricture were enrolled. They had cytologically or histologically proven unresectable biliary-tract carcinoma with hilar biliary stricture type IIIa or IV according to Bismuth's classification. INTERVENTIONS: Endoscopic 3-branched partial stent-in-stent deployment of MS in hilar biliary strictures by using a JOSTENT SelfX stent. MAIN OUTCOME MEASUREMENTS: The success rate of the procedure, stent patency time, reinterventions, and complications. RESULTS: Endoscopic 3-branched partial stent-in-stent deployment was successfully accomplished in all cases. The MS became obstructed in 3 cases (33%), mean 1.5 months, range 1.4 to 2.7 months. However, no MS obstruction occurred in the other 6 patients (67%), mean 11 months, range 4.7 to 16.4 months. In the obstructed cases, the deployment of 2 or 3 tube stents was completed successfully. One case of cholecystitis was observed as a short-term complication. LIMITATION: The small number of cases. CONCLUSIONS: Endoscopic 3-branched partial stent-in-stent deployment of a JOSTENT SelfX stent was effective in selected patients with high-grade malignant hilar biliary stricture.