The decision to undertake transplantation in a patient with fulminant liver failure requires consideration of many factors so that the physician may arrive at the most appropriate course of action. There are several definitions of fulminant liver failure used in current practice, all excluding patients with chronic liver disease. In the one most recently proposed, the terms hyperacute, acute and subacute liver failure are used to categorize groups of patients with different clinical appearances and progress. Patients in the hyperacute group have a better outcome with medical treatment than others, despite deeper levels of encephalopathy. The decision to proceed to transplantation should be undertaken in patients who fulfil criteria for a poor prognosis with medical management. For two groups, Hôpital Paul Brousse, Paris, and King's College Hospital, London, criteria are based on analysis of large patient numbers, which can be applied at the bedside without recourse to complex analysis. Once a patient has been listed for transplantation, regular systems review must be undertaken because the development of irreversible multiple organ failure may preclude transplantation. Hepatectomy may occasionally have a role in stabilizing a patient awaiting a suitable organ. In less severe cases, auxiliary liver transplantation has been undertaken, and in some patients regeneration of the native liver has occurred, allowing withdrawal of immunosuppressive therapy. The results of orthotopic liver transplantation in fulminant liver failure have steadily improved over recent years, with reported 1-year survival rates of up to 80% in some series, yielding a good prognosis for certain groups of patients who previously had unacceptably high mortality.