Background: The role of interleukin-lß in the pathogenesis of sepsis is widely accepted, but less is known regarding its role in the newborn period. Objective: The aim of the work wasto detect relation between serum level of IL- lß and clinical presentation of neonatal sepsis. Patients and Methods: This case control trial study included a total of thirty-six newborns, attending at the Neonatal Intensive Care Unit, Zagazig University Hospitals. They were categorized into two groups; 18 each: Group I: newborns with suspected clinical sepsis, and Group II (control group) healthy newborns with no sepsis. Interleukin- lß was assessed in all neonates. Results: IL-lß showed significant increase in diseased versus control group (20.07±8.68 versus 1.21±0.48, respectively with p <0.001). IL-lß showed insignificant difference in preterm versus full term neonates. IL-lß showed significant difference in subgroup analysis. Full term neonates in patient group had the highest mean (23.811±10.55 pg/ml, p < 0.001). Conclusion: It could be concluded that premature babies have lower IL-1ß serum concentrations, while mature newborns with sepsis had higher IL-1ß serum concentrations than healthy newborns.