Systemic inflammatory response syndrome may be viewed as the systemic expression of cytokine signals that normally function on an autocrine or paracrine level. Sepsis is defined as systemic inflammatory response syndrome caused by an infection. Multiple organ dysfunction syndrome may represent the end stage of severe systemic inflammatory response syndrome or sepsis. Many cells are involved, including endothelial cells and leukocytes and multiple proinflammatory and antiinflammatory mediators (cytokines, oxygen free radicals, coagulation factors; and so forth), Various pathophysiologic mechanisms have been postulated. The most popular theorys that the inflammatory process loses its autoregulatory capacity; however, microcirculatory dysregulation and apoptosis may also be important, and a new paradigm posits a complex nonlinear system. Many new treatments have been studied recently. The usefulness of immune modulating diets remains to be evaluated, Molecular immunomodulation is still of unclear value. The therapy of sepsis:and multiple organ dysfunction syndrome remains mainly supportive. Curr Opin Pediatr 2001 13:247-253 (C) 2001 Lippincott Williams & Wilkins, Inc.