Sepsis has recently been redefined as acute organ dysfunction due to infection. The ED plays a critical role in identifying patients with sepsis. This is challenging due to the heterogeneity of the syndrome, and the lack of an objective standard diagnostic test. While overall mortality rates from sepsis appear to be falling, there is an increasing burden of morbidity among survivors. This largely reflects the growing proportion of older patients with comorbid illnesses among those treated for sepsis.