Retrospective analyses have shown a 20-40 % incidence of R1 resection in hilar cholangiocarcinoma, which therefore represents a significant issue to be addressed.We have reviewed the literature on the impact of R1 resection in hilar cholangiocarcinomas and on possible surgical options to increase the rate of complete tumour resections.To minimise the rate of R1 resections a preoperative risk assessment concerning the predisposed anatomic locations is required. During planning of the surgical strategy, liver function plays a central role prior to right-sided hemihepatectomies. Due to the loss of a high amount of functional liver parenchyma, contralateral portal vein embolisation is often used prior to right trisectionectomies. For left-sided hepatectomies the management of the right hepatic artery is fundamental. The right hepatic artery has a very close contact to the tumour region, although arterial invasion is rarely seen. However, the risk of manifest or occult R1 resection is relatively high along the right artery. In selected cases an arterial resection might be considered, but this increases the risk of postoperative complications. Arterial resection might be performed either via direct anastomosis or by using an interposition graft. As reserve procedures preoperative embolisation of the hepatic artery without reconstruction or an arterialisation of the portal vein are available. However, the latter two procedures come along with an increased rate of biliary complications. In selected lymph-node negative patients with irresectable hilar cholangiocarcinoma liver transplantation might be considered.Despite significant advances in surgical technique, R1 resection remains a problem, which is aggravated by the lack of evidence-based adjuvant measures.