Objectives: Neonatal sepsis is clinical syndrome of bacteremia with systemic signs and symptoms. Neonatal sepsis is still a leading cause of mortality in neonatal intensive care units all over the world. Early diagnosis and treatment of the newborn infant with suspected sepsis are essential to prevent severe and life threatening complications. Objective: The aim of this study was to evaluate polymorph nuclear (PMN) leucocyte elastase as a diagnostic tool in neonatal sepsis. Subjects and Methods: This study was conducted on 45 full term and preterm neonates suspected as neonatal sepsis compared to 45 apparently healthy neonate with matched age and sex, as a control group. Results: 55.6% of our patients group were full-term patients and 44.4% were preterm. All the patients were subjected to full history taking, full clinical examination, lab investigation including CBC, CRP, blood culture and sensitivity, and measurement of serum polymorph nuclear leucocyte elastase enzyme. Conclusion: Significant elevation of serum polymorph nuclear leucocyte elastase level in neonatal sepsis with high specificity.