Background: L1 promotes cell proliferation, migration, invasion and tumorigenesis in cancer cells.It is expressed in some type of cancer cells such as lung cancer, malignant melanoma, ovarian and uterine carcinoma, and colorectal carcinoma.There is no previous report on the expression of L1 in extrahepatic cholangiocarcinoma (ECC) and its clinical significance.Therefore, we investigated the expression of L1 with related molecules in 67 patients with ECC and estimated the correlation between expression of these proteins and the clinicopathologic characteristics.Material and Method: We investigated 67 patients of ECC who underwent surgical resection.The paraffin-embedded sections were stained with anti L 1, EGFR, E-cadherin and β-catenin.We analyzed the correlation between these antibodies and clinicopathologic outcomes.Results: L1 and EGFR were highly expressed in ECC (41.8% and 74.6%, respectively).L1 was mostly expressed in the poorly differentiated and invasive front of tumor cells.Reduced membranous expression of E-cadherin and β-catenin was61.2% and 89.6%, respectively.β-catenin was also expressed in the nuclei (13.4%) of cancer cells.According to survival analysis, high expression of L 1 and β-catenin nuclear expression were significantly related to poor survival for overall survival (p=0.0000 and p=0.0057 ,respectively) and disease free survival (p=0.0022 and p=0.0014, respectively).Multivariate analysis pointed out that L1 expression was an independent prognostic factor for overall survival (HR=2.847, P=0.000).Conclusion: L1 and EGFR are commonly expressed in the ECC and L1 expression is correlated with aggressive clinical course.In addition, E-cadherin and β-catenin membranous expression are commonly reduced in the ECC.Anti-L1 CAM immunotherapy may improve survival of patients.