BACKGROUND/AIMS Preoperative portal vein embolization (PVE) allows potentially curative hepatic resection to be carried out in patients with hepatobiliary malignancies who are otherwise not candidates for resection because of the small size of the future liver remnant (FLR). However, there have only been a few reports on PVE before hepatectomy for hilar cholangiocarcinoma due to the small number of patients who can be treated with radical surgery. METHODOLOGY Between January 2007 and March 2009, 49 consecutive patients with hilar cholangiocarcinoma who were planned to have hemi-hepatectomy/extended hemi-hepatectomy plus caudate lobe resection in our tertiary referral center were studied. The change in size of the FLR and the operative outcomes were compared between patients with or without PVE. RESULTS All patients had liver dysfunction as a result of biliary obstruction due to hilar cholangiocarcinoma although they had all received percutaneous transhepatic biliary drainage. PVE was used in 16 patients with an estimated FLR of <50%, while no PVE was carried out in 33 patients with an estimated FLR of >50%. Complications after PVE occurred in 3 patients (18.8%), which included bile leakage (n=1) and coil displacement (n=2). No complication precluded liver resection. The FLR to total liver volume (TLV) ratio at presentation was significantly smaller in patients who underwent PVE than those who did not undergo PVE (40.3 +/- 7.4% vs. 56.6 +/- 5.0%; p < 0.001). After PVE, the FLR to TLV ratio increased significantly (40.3 +/- 7.4% vs. 43.1 +/- 7.0%; p < 0.001) at a mean time of 14.2 +/- 3.5 days. The mean +/- S.D. increase in FLR was 4.6 +/- 3.0 cm3/day. At surgery, the FLR volume was still significantly smaller in the PVE group than the non-PVE (802 +/- 216 cm3 vs. 979 +/- 202 cm3; p = 0.007). In the PVE group, insufficient hypertrophy of the FRL prevented one patient from having surgery, while local tumor progression and peritoneal dissemination precluded hepatectomy in 2 more patients. Finally, 13 patients (81.3%) underwent radical surgery. The PVE group had similar complication and mortality rates compared with the non-PVE group (complication rate, 69.2% vs. 63.6%; mortality rate, 0.0% vs. 9.1%). The 1- and 2-year overall survivals for the PVE group (with intent-to-treat analysis), PVE group (radical surgery only) and the non-PVE group were 57.3% and 43.0%; 71.3% and 53.5%; 70.4% and 54.4%, respectively. There was no significant difference in the survival outcomes. CONCLUSIONS The results suggested that PVE is a safe and efficacious procedure in inducing adequate hypertrophy of the FLR before major hepatic resection for hilar cholangiocarcinoma with obstructive jaundice which had been relieved by percutaneous transhepatic biliary drainage.