Purpose To evaluate the efficacy and safety of hepatic arterial infusion (HAI) of oxaliplatin and 5-fluorouracil for advanced perihilar cholangiocarcinoma (PCC) in this prospective phase II study. Materials and Methods The protocol was approved by the local ethics committee, and all patients gave informed consent. Patients with nonresectable PCC were included in a prospective, open phase II study investigating HAI through interventionally implanted port catheters. HAI consisted of infusions of oxaliplatin 40 mg/m2 for 2 hours, followed by 5-fluorouracil 800 mg/m2 for 22 hours on days 1-3 every 3-4 weeks. A maximum of six cycles of HAI were applied for tumor control patients followed by maintenance with oral capecitabine until tumor progression. The primary end points were tumor response and progression-free survival (PFS). The secondary end points were local PFS, overall survival, and adverse events. Kaplan-Meier methodology and Cox regression analysis were used to evaluate the risk factors for survival. Results Between 2012 and 2015, 37 patients were enrolled. The overall response rate was 67.6% (25 of 37), and the disease control rate was 89.2% (33 of 37). Median PFS, local PFS, and overall survival were 12.2, 25.0, and 20.5 months, respectively. All three survival lengths in patients with periductal infiltrating pattern were found to be significantly longer than those in patients with mass-forming pattern (P < .001, hazard ratio < 0.2). Macroscopic growth patterns (P = .018) and number of HAI cycles (P < .001) were independent risk factors of survival. The most frequent adverse events were grades 1 and 2 gastrointestinal side effects and sensory neuropathy in 31 (83.8%) and 28 (75.7%) patients, respectively. Conclusion HAI with oxaliplatin and 5-fluorouracil may be an encouraging treatment choice for advanced PCC due to its high tumor control, survival benefit, and low toxicity, especially in patients with periductal infiltrating pattern. © RSNA, 2016.