Background: Surgical resection is required for curative treatment of patients with extra-hepatic cholangiocarcinoma (EH-CCA). The objective of this study was to determine if the distance of surgical margin was associated with outcome. Methods: Patients who underwent curative-intent resection for EH-CCA between 2000 and 2015 at 10 hepatobiliary centers across the U.S. were evaluated using prospectively collected data. Cox proportional hazard model was utilized to evaluate the influence of the extent of the margin on outcome. Results: 538 patients with EH-CCA who underwent curative-intent resection were included: 383 (71%) undergoing R0 resection, 153 (28%) undergoing R1 resection, and 2 with R2 resection. A negative surgical margin (R0) was associated with improved recurrence-free (RFS) and overall survival (OS) (RFS: 10.5% vs. 3.6% (R1) and OS: 25.8% vs. 9.3% (R1). Subsequently, further analysis on 161 patients with complete data on distance of resection margin, all undergoing R0 resection, was performed to assess the impact of extent of margin on outcome. On multi-variable analysis, the resection margin distance, analyzed as a continuous variable, was not associated with either improved RFS (RR 1.00, 95% CI 0.96-1.05; p 0.71) or OS (RR 0.99, 95% CI 0.96-1.01; p 0.49). Increasing age, increased tumor size, and LN metastasis were identified as independent predictors of OS; while RFS were mainly dependent on tumor size and LN metastasis (Table). Conclusions: Achieving R0 resection is acceptable for EH-CCA tumors, and obtaining additional margin does not confer a benefit on overall survival. Increasing age, tumor size, and LN metastasis are independent predictors of RFS and OS, but increased margin width is not associated with improvement in either. Multivariable analysis of factors affecting OS of patients with extra-hepatic CCA who underwent surgical resection, with significant factors noted in bold.