Objective: One of the most challenging aspects in the management of neonates with late-onset neonatal sepsis (LOS) is to make the diagnosis. Presepsin is a novel and promising marker of sepsis. The aim of this study was to assess the role of presepsin in the diagnosis of LOS in preterm infants.Methods: Forty-two premature newborns 32 weeks gestational age with a diagnosis of LOS were prospectively involved in the study. Forty gestational and postnatal age-matched infants without sepsis served as controls. Levels of presepsin, C-reactive protein, and procalcitonin were measured at enrollment and on the third and seventh days of sepsis.Results: Initial presepsin levels in the LOS group were significantly higher than in the control group (1024pg/mL, min-max: 295-8202; versus 530pg/mL, min-max: 190-782; p<0.0001). The area under the receiver-operating curve for presepsin was 0.864. A presepsin value of 800.5pg/mL was established as a cut-off value, with 67% sensitivity and 100% specificity. Presepsin levels gradually decreased during treatment.Conclusion: Presepsin can be used as a reliable biomarker for LOS and treatment response in preterm infants. However, we could not demonstrate the efficacy of presepsin for the detection of disease severity or prognosis.