BACKGROUND: There are few comparative data as to whether plastic or self-expanding metallic stents are preferable for palliating malignant hilar biliary obstruction. METHODS: Thirty-day outcomes of consecutive endoscopic retrograde cholangiopancreatographies performed for malignant hilar obstruction at 6 private and 5 university centers were assessed prospectively. RESULTS: Patients receiving plastic (N=28) and metallic stents (N=34) were similar except that metallic stent recipients more often had: Bismuth III or IV tumors (16/34 vs. 5/28 P=0.043), higher Charlson comorbidity scores (P=0.003), metastatic disease (P=0.006), and management at academic centers (P=0.018). The groups had similar rates of bilateral stent placement (4/28 vs. 5/34), and similar frequency of opacified but undrained segmental ducts (7/28 vs. 5/34). Adverse outcomes including cholangitis, stent occlusion, migration, perforation, and/or the need for unplanned endoscopic retrograde cholangiopancreatography or percutaneous transhepatic cholangiography occurred in 11/28 (39.3%) patients with plastic versus 4/34 (11.8%) with metal stents (P=0.017). By logistic regression, factors associated with adverse outcomes included plastic stent placement (odds ratio 6.32; 95% confidence interval 1.23, 32.56) and serum bilirubin (1.11/mg/dL above normal: 1.01, 1.22) but not center type or Bismuth class. CONCLUSIONS: Metallic stent performance was superior to plastic for hilar tumor palliation with respect to short-term outcomes, independent of disease severity, Bismuth class, or drainage quality.