Morbidity and mortality in intensive care units is increasingly attributable to a syndrome characterized by systemic inflammation and organ dysfunction. Recently, the label systemic inflammatory response syndrome (SIRS) has been coined to identify patients with this condition, regardless of the cause. Clinical studies in both adults and children have demonstrated that the population at risk for SIRS is similar to those at risk for adult respiratory distress syndrome (ARDS). Thus, there is a growing recognition that SIRS leads to ARDS, and similarly, systemic abnormalities associated with ARDS often lead to SIRS. Recent discoveries suggest that the interaction between the inflammatory system and the endothelium is the common pathophysiologic mechanism for both SIRS and ARDS, and provides the focus for new treatment as well as modifications of older therapies.