Procalcitonin (PCT), a soluble protein composed of 116 amino acids with a sequence identical to that of the calcitonin prohormone, has been considered as a reliable biomarker for evaluating of bacterial infection and sepsis. In healthy individuals, serum PCT concentrations are undetectable, however, in case of severe bacterial infections and sepsis, it increase rapidly released mainly in peripheral blood mononuclear cells and modulated by bacterial lipopolysaccharides (LPS) and sepsis-associated cytokines. An increase number of studies have demonstrated that PCT-guided strategy is a helpful approach to guide antibiotic administrations and clinical interventions in the intensive care unit (ICU).