Background: The conformability of uncovered self-expandable metal stents (SEMSs) plays an important role in maintaining stent patency. However, whether increased conformability can prolong the duration of SEMS patency remains to be proved. Objective: The aim of this study was to examine the efficacy and complication rates of the Niti-D biliary uncovered metal stent (NDS), which is more conformable than the uncovered Wallstent. Design: Nonrandomized, retrospective study. Setting: Tertiary-care academic medical center. Patients: From March 2005 to July 2007, 101 patients received an NDS (41 cases) or a Wallstent (60 cases) for malignant biliary obstruction. Interventions: SEMS placement. Results: Stent occlusion occurred in 11 patients (26.8%) with the NDS and 17 patients (28.3%) with the Wallstent. The median duration of stent patency tended to be longer for the NDS group (153 days) than for the Wallstent group (124 days); however, the difference was not statistically significant (P = .204). The median duration of overall survival of patients was 160 days for the NDS and 148 days for the Wallstent. The subgroup analysis showed that 27 patients had hilar obstruction (NDS 13, Wallstent 14). The median duration of stent patency was 249 days for the NDS group and 76 days for the Wallstent group; this difference was statistically significant (P = .006). The complications included pancreatitis in 3 NDS cases and 5 Wallstent cases. Limitation: The absence of prospective randomized recruitment. Conclusion: The results of this study showed no significant differences between the NDS and the Wallstent for the palliative endoscopic management of malignant biliary obstruction. There were no significant differences in patency, complication rates, and patient survival between the more conformable NDS and the conventional Wallstent. However, the NDS, which has good conformability, may be preferred for hilar obstruction.