Acute liver failure is a rare but life-threatening critical illness in which there is rapid deterioration of liver function in a previously healthy individual. The involvement of other organs makes acute liver failure an extremely difficult condition to manage. The intensive care unit (ICU) has a pivotal role in the management of this condition by providing support for failing organs while allowing time for hepatic regeneration or for pre-optimization prior to liver transplantation. There are numerous causes for acute hepatic failure but Paracetamol poisoning remains the leading cause in the United Kingdom. Miscellaneous causes of hepatic failure include adult-onset Still's disease, heatstroke, and primary graft non-function in liver transplant recipients. Potential complications of acute liver failure include seizures, haemorrhage, infection, renal failure and metabolic imbalances. All patients with clinical or laboratory evidence of moderate or severe acute hepatitis should have immediate measurement of prothrombin time (PT) and careful evaluation of mental status.