 Platelets play a central part not just in homeostasis and thrombosis as the primary effector cells, but they are also key cells in the regulation of the immunological response to various stressors. After activation, platelets release their granules which store different inflammatory mediators that induce coagulation, recruit further platelets, activate complement, attract neutrophils and leukocytes and regulate the vascular tone. Platelets activated by systemic inflammation and infection, may also contribute to the development of multiple organ failure. Thus, inhibition of platelet activation may have beneficial effects on critically ill patients. 