Early diagnosis of the different severities of septic inflammation is important for early implementation of specific therapies. Sepsis and severe sepsis are accompanied by clinical and laboratory signs of systemic inflammation. However, patients suffering from non-infectious inflammation may present with similiar signs and symptoms making it difficult to diagnose infection based on clinical findings alone. Bacteriological evidence of sepsis, though definitive and specific, may not be obtainable, is time-consuming and even may not occur concurrently with clinical signs of sepsis. It is therefore important to identify markers, which, by enabling an early diagnosis of sepsis and organ dysfunction, would allow early specific therapeutic interventions. Wheras C-reactive Protein is a more sensitive parameter for the diagnosis of non-systemic infections, Procalcitonin seems to be a useful parameter to improve the diagnosis and monitoring of therapy in patients with severe sepsis and septic shock.