Sepsis, as defined by an expert consensus definition, is the development of the systemic inflammatory response syndrome in the presence of infection. Using this clinically applicable definition, several studies have evaluated the epidemiology of sepsis over the past decade. The current incidence of sepsis is at least 240 patients per 100,000 people in the United States population, whereas for severe sepsis it is between 51 and 95 patients per 100,000 people. The incidence rate for sepsis has been increasing over the past two decades, driving an increase in the number of deaths despite a decline in case-fatality rates. Sepsis is the tenth leading cause of death in the United States and accounts for more than 17 billion dollars in direct healthcare expenditures.