Aim: The aim of this study was to detect the most common causative organism causing neonatal sepsis in women suffered preterm prelabour rupture of membranes and if it is different from that of the maternal genital swab.Materials and Methods: This study was carried out on 200 pregnant women with PPROM at gestational age                           between 23 weeks plus 6 days to 28 weeks. Genital swabs were taken for microbiological study and all women were managed conservatively. After delivery, buccal and nasal swab were taken from the neonates and the detected organism(s) were correlated with those detected from the mothers' swabs. Also, neonatal outcome was studied regarding incidence of neonatal sepsis, Neonatal Intensive Care Unit) admission and neonatal mortality.Results: From the 200 enrolled cases and their neonates, there were thirty-three neonates (16.5%) that were admitted to the NICU with twenty-one neonates (67.8%) of them suffering neonatal sepsis. Only thirteen neonates (61.9%) of those who had suffered sepsis shared the same organisms with their mothers. The other eight cases (38.1%) had different organisms. The most frequent organism regarding maternal vaginal swabs was Escherichia coli followed by Group B Streptococci sharing the same frequency with non-hemolytic Streptococci, Staphylococcus aureus and Group A streptococci sharing the same frequency with Klebsiella species.Conclusion: E-coli is the most common causative organism for neonatal sepsis in PPROM before 28 weeks of gestation.