Correlations between circulating endotoxin levels from the blood of septic patients with clinical outcome measures have proven to be rather difficult. The clinical impact of endotoxin in septic patients depends upon the kinetics of LPS release, the concentration of LPS binding proteins, the cellular responsiveness to endotoxin, and numerous other immunogenetic, microbiological and physiological variables. Failure to account for these variables adequately has limited the clinical utility of endotoxin measurement. Several clinical studies have associated high levels of LPS with an excess risk of morbidity and mortality in sepsis that is largely independent of the nature of the micro-organism responsible for the septic episode.