Acute liver failure (ALF) and acute on chronic liver failure (ACLF) are conditions frequently encountered in the ICU and are associated with high mortality. The purpose of these guidelines was to develop evidence-based recommendations addressing common clinical questions surrounding the unique manifestations of liver failure in the critically ill patient. Often, clinical care must be adapted to individual clinical circumstances and patient/family preferences. These guidelines are meant to supplement and not replace an individual clinician's cognitive decision-making. The primary goal of these guidelines is to aid best practice and not represent standard of care.