Severe sepsis is a life-threatening complication of infection. Due to associated organ-failure treatment in an Intensive Care Unit is usually indicated. Since sepsis is defined by the combination and progression of clinical events, correct definitions are essential to enable good comparison between study results and determination of suitable treatment. Severe sepsis is associated with a mortality of 20-60% and decreases the health-related quality of life in survivors. It is estimated that annually in the Netherlands 9000 patients are admitted to an Intensive Care Unit with severe sepsis. Direct medical costs of severe sepsis are estimated at [symbol: see text] 19,500 per patient. Costs correlate strongly with the length of stay. Annually Euro dollar 168,6 million is spent on severe sepsis, which represents 0.5% of all health-care costs and 1.7% of the annual hospital budget in the Netherlands.