Sepsis is a complex and lethal condition. For successful treatment, clinicians need high quality testing to guide the approach to pathogen identification and treatment. Medical laboratories play a vital role in the detection of infectious agents, and must continually strive to discover new and reliable tests and to analyze the reliability of existing tests in different diseases and expand their usage as appropriate. Selecting the appropriate therapy, reducing the use of antibiotics and thereby reducing antibiotic resistance are also undeniable parts of this task. The most commonly used parameters to guide infection therapy are the white blood cell count, the erythrocyte sedimentation rate, the absolute count of neutrophils, the absolute number of lymphocytes, and the level of C-reactive protein, serum amyloid A protein, ceruloplasmin, haptoglobin, fibrinogen, and procalcitonin (ProCT). Although ProCT has been accepted as quite effective in differentiating serious bacterial infections, there are unresolved questions regarding effective usage during follow-up, as there are with other markers. ProCT and other promising biomarkers in a sepsis setting were the focus of this review, beginning with the first study to define ProCT in the literature, and examining some of the studies related to the importance of the ProCT-sepsis relationship, and detailed information on candidate markers.Keywords: Biomarker, C-reactive protein, procalcitonin, reference interval, sepsis.