Despite advances in the use of newer antimicrobials and aggressive supportive care, sepsis and its sequalae remain a major source of morbidity and mortality in the neonate. The VLBW neonate is especially at high risk. We and others have demonstrated that neonatal MNC are deficient in their production of G-CSF and GM-CSF, which, in part, may explain the neonates propensity to develop neutropenia during times of sepsis. G-CSF and GM-CSF have been shown to both enhance neonatal neutrophil superoxide production in vitro and to increase circulating neutrophil numbers through expansion of the NSP in the BM in neonatal rats and humans. G-CSF is protective (if given with or before antibiotics) during experimental GBS in the neonatal rat and appears to be well tolerated (both short term and 2 years after its use) in the human neonate. In a phase II randomized pilot multicenter study, GM-CSF prophylaxis in the VLBW neonate was well tolerated during 4 weeks of administration and was noted to have significantly reduced the incidence of nosocomial infections. Future efficacy and safety studies in more neonates need to be completed and assessed before the routine pharmacologic use of G-CSF or GM-CSF is recommended to prevent and treat neonatal sepsis.