There have been many attempts to provide a uniform definition for the diagnosis of sepsis that can be used for research and clinical purposes. Several definitions are too broad and, as a result, clinicians are unable to direct appropriate therapies to patients. Disappointing immunomodulatory trials have led many researchers to the conclusion that the current diagnostic criteria of sepsis fails to identify patients who could benefit from immunomodulatory therapies. In order to restore clinical and experimental relevance, many researchers and clinicians believe that sepsis should be defined as an inflammatory response to infection with signs of remote organ dysfunction. However, because common clinical signs of systemic inflammation are neither specific nor sensitive for sepsis, other markers may be helpful. Markers of the systemic inflammatory response to infection could include cytokines such as tumour necrosis factor alpha, interleukin 1, 6 and 8 and the propeptide procalcitonin. As well as identifying patients who may benefit from pro- or anti-inflammatory therapies, these markers may gauge the extent of the inflammatory response and could be used for monitoring the immune status of the patient.