Postoperative liver failure is a severe complication of major hepatectomies, in particular in patients with a chronic underlying liver disease. Preoperative interruption of the portal flow in the liver territories planned to be removed, induces their atrophy and the compensatory hypertrophy of the segments spared by the resection. This interruption can be induced by the surgical ligation of the portal branches or by the percutaneous intraportal injection, under ultrasound guidance, of glues or sclerosing agents. Preoperative portal vein embolisation is usually indicated when the remnant liver accounts for less than 25-40% of the total liver volume. Feasibility is close to 100% and the risk comparable to that of a percutaneous liver biopsy. It is well tolerated and the biological impact is minimal in patients without liver failure. Compensatory hypertrophy of the non-embolised segments is maximal during the first 2 weeks and persists, although to a lesser extent during approximately 6 weeks. The magnitude of hypertrophy is correlated with the volume of parenchyma embolised, and is reduced in diabetic or jaundiced patients or when there is an active chronic liver disease. Liver resection is performed 2 to 6 weeks after embolisation. Retrospective studies and one prospective study suggest that patients so prepared have a reduced perioperative risk and that their long term carcinologic results are not impaired.