We describe the technique of mesohepatectomy including caudate lobectomy and resection of hilar bifurcation with biliary reconstruction by 6 hepaticoejunostomies for a Klatskin tumor type IV. This technically demanding approach does not only require careful vascular dissection to maintain blood supply and venous drainage of the two remaining liver parts but it also bears the risks of bilateral biliary reconstruction and of two resection surfaces. The major advantage of mesohepatectomy in comparison to extended hepatectomy is the preservation of functioning liver tissue. Therefore, despite its technical challenges, mesohepatectomy may be an attractive alternative in selected cases of advanced hilar cholangiocarcinoma in which an extended liver resection is contraindicated due to the small amount of remaining liver tissue. In these cases mesohepatectomy reduces the risk for postoperative liver insufficiency but still allows oncologic tumor resection.