The incidence of sepsis and SIRS, respectively is still rising. Mortality is 40 to 70% and, thus, remains very high in spite of major advances in intensive care medicine. Numerous experimental data have helped to explain isolated aspects of the pathophysiology of these disease states but the complex patho-mechanism remains to be elucidated. The discovery of the toll-like receptors and of the endotoxin-binding proteins LBP and BPI have substantially contributed to the understanding of the bacterial toxin-host interactions and may stimulate the development of new therapeutic strategies in the future. Pro- and anti-inflammatory cytokines play a central role in disease evolution, however the concept of organ-derived and organ-specific damage is gaining importance. Both inflammation and counter-regulation can occur at the same time in the circulation thus, making the evaluation of the patients' immunological status difficult. Additionally, several gene polymorphisms have been detected for example within the toll-like receptor genes and TNF genes. These polymorphisms document the existence of pre-disposing factors, which influence acute phase reaction as well as immuno-competence in sepsis. Both genes and gender will play an important role in the future to identify patients at risk and potentially, to design a specific and individualized immuno-therapies.