Background Gallbladder and extrahepatic biliary malignancies are aggressive tumors with high risk of recurrence and death. We hypothesize that elevated preoperative Neutrophil-Lymphocyte Ratios (NLR) are associated with poor prognosis among patients undergoing resection of gallbladder or extrahepatic biliary cancers. Methods Patients who underwent complete surgical resection between 2000–2014 were identified from 10 academic centers (n=525). Overall (OS) and recurrence-free survival (RFS) were analyzed by stratifying patients with normal (<5) versus elevated (>5) NLR. Results Overall, 375 patients had NLR <5 while 150 patients had NLR >5. Median OS was 24.5 months among patients with NLR<5 versus 17.0 months among patients with NLR>5 (p<0.001). NLR was also associated with OS in subgroup analysis of patients with gallbladder cancer. In fact, on multivariable analysis, NLR>5, dyspnea and preoperative peak bilirubin were independently associated with OS in patients with gallbladder cancer. Median RFS was 26.8 months in patients with NLR<5 versus 22.7 months among patients with NLR>5 (p=0.030). NLR>5 was independently associated with worse RFS for patients with gallbladder cancer. Conclusions Elevated NLR was associated with worse outcomes in patients with gallbladder and extrahepatic biliary cancers after curative-intent resection. NLR is easily measured and may provide important prognostic information.