Background: Neonatal sepsis remains a challenge for neonatal care providers OBJECTIVES: The objective of this study was to compare red blood cell distribution width (RDW) in non- septic and septic neonates and to investigate the relationship between red blood cell distribution width (RDW) and severity of neonatal sepsis. METHODS: This case control study was carried out on 100 full term neonates divided to (40)non septic neonates as control group and (60) septic neonates as study group which was subdivided according to severity of sepsis to (3)subgroups;(1)sepsis group (21 case),(2)sever sepsis group (19 case) and (3)septic shock group( 20 case).An approval from Research Ethics Committee in Benha faculty of medicine was obtained and written consents were obtained from parents. Neonates were subjected to: History taking, clinical examination for manifestations of sepsis. Investigations such as: Complete blood count including RDW %, C- reactive protein, Blood culture were also done. RESULTS: The mean and median values of RDW (16.1, 16.3) were significantly higher among cases than controls. Also RDW was significantly higher among septic shock patients (17.6%) than sepsis and severe sepsis ones (14.8 and 16.0 respectively).P