Cirrhotic patients who developed a decompensation episode requiring an admission to an intensive care unit are not equal in term of prognosis. This led to the definition of a syndrome, acute-on-chronic liver failure (ACLF), marked by the severity of systemic inflammation, the development of organ failures and a high short-term mortality. The most common underlying liver etiology is related to acute alcohol hepatitis in western countries and to HBV or HCV cirrhosis in eastern countries. Twenty-eight and 90-days high mortality rates are well linked to the number of organ failure and defined, merely ten years ago, by a modified SOFA score. ACLF is a dynamic syndrome and grading can vary from hospital admission. ACLF grading between day 3–7 of admission is more accurate for determining outcome. ACLF-3 patients with ≥3 organ failures remain very challenging with >75% mortality rate. Despite recent advances in the medical management of critically ill cirrhotic patients, the prognosis of these patients remains poor. Currently, the main effective treatment is an urgent liver transplantation (LT) which is performed in a very selected patients eligible to transplant given the limited availability of organ donors and the low post-transplant survival rates reported in earlier studies. Recently, large retrospective multicenter studies and registries showed an improved 1-year post-transplant survival rate >83% in several transplant centers. Nevertheless, only few proportions of the ACLF-2 and ACLF-3 patients are transplanted representing 0–10% of most liver transplant programs. A careful selection of these patients (excluding major comorbidities i.e., older age, addictology criteria, severe malnutrition…) and optimal timing for transplant (infection control, hemodynamic stability, low oxygen and vasopressor requirements) are associated with excellent post-transplant survival rate.