The systemic inflammatory response (SIRS), sepsis and septic shock are termed collectively the septic syndromes and are leading causes of morbidity and mortality amongst patients admitted to the intensive care unit (ICU). The pathophysiology of the syndromes is consequent upon the interaction between the infecting agent (or insult) and the host immune response. Persistence of the immune response and continued oxidative stress are thought to be key components. The purpose of this project was to investigate the implications of HO-1 expression on the inflammatory response, using in vivo, in vitro and ex vivo models.