Multiple organ failure continues to be the primary cause of death after trauma and sepsis. This clinical syndrome represents the transition from a hypermetabolic response to injury to a syndrome of progressive organ failures and death. Risk factors include: perfusion deficits, persistent foci of dead or injured tissue, an uncontrolled focus of infection, the presence of the respiratory distress syndrome, persistent hypermetabolism, and preexisting fibrotic liver disease. Once initiated, most treatment modalities for the organ failure syndrome become progressively ineffective including: ventilation, antibiotics, nutrition, and surgery. The best treatment remains prevention and rapid control of risk factors including restoration of oxygen transport and aggressive nutrition support. There seems to be no treatment "magic bullet" either experimentally or clinically once the syndrome has occurred. The metabolic response to injury involves alterations in physiology and in the metabolism of carbohydrate, fat and amino acids. These changes seem to reflect the modulation of the end-organs by the mediator systems activated in response to the stress stimuli. The transition from hypermetabolism to organ failure appears to reflect the clinical appearance of liver failure. It is hypothesized that this liver failure may represent a state of regulatory dysfunction induced in large part by the activated hepatic macrophage, the Kupffer cell. The activation of these macrophages is hypothesized to represent the final stage of a series of stimulating events, eg. hypoxia, endotoxin, bacteria, and gut translocated toxins. The precise monokine(s) responsible are not yet completely characterized, although Interleukin-1 (IL-1) and tumor necrosis factor (TNF) appear to be involved as do prostaglandins (Pg) such as PgE2.(ABSTRACT TRUNCATED AT 250 WORDS)