As smaller babies survive in neonatal intensive care units, late-onset septicemia with unusual pathogens appears. Between 1 January and 31 December 1998, in Hacettepe University Ihsan Dogramaci Children's Hospital Neonatal Intensive Care Unit, seven infants had S. marcescens isolates. Four babies had septicemia with the microorganism. The case fatality rate was 50 percent in infants with S. marcescens septicemia. The combination of ceftazidime or imipenem with amikacin appears appropriate for the treatment of newborns with Serratia infection.