Critically ill patients in varying degrees of liver failure are catabolic and consequently require expeditious caloric support. Unique problems in this group of patients essentially revolve around the diagnosis and management of hepatic encephalopathy. From the overview provided in this article, it can be concluded that, only in overt hepatic coma, should all nitrogen products be withheld while precipitating causes are evaluated. Protein should be reintroduced as rapidly as possible to avoid the consequences of protein deprivation. Once the acute intercurrent illness has resolved, the cirrhotic patient returns to baseline energy and protein requirements indistinguishable from the population at large.