Procalcitonin (PCT) is a biomarker that is increasingly being used to help in decision making when managing febrile patients. This is a non exhaustive review of the literature regarding the use of PCT in deciding to begin or discontinue antibiotic treatment. PCT appears to be useful in patients with respiratory infections or sepsis. In both these situations and using evaluated algorithms, a low PCT (< 0.25 microg), enables withholding or discontinuing antibiotic treatment, without negatively affecting clinical outcomes. For other indications there is however insufficient evidence to support the systematic measurement of PCT in all febrile patients. In particular, in patients with autoimmune disease or in the postoperative setting, PCT is insufficiently sensitive or specific to rule out or confirm a bacterial infection requiring antibiotic treatment.