Enterobacter cloacae has emerged as an important pathogen in neonatal units, with several outbreaks of infection being reported. The aim of this study was to investigate an outbreak of sepsis due to E. cloacae in a neonatal unit and to review the literature. A retrospective cohort study was conducted in which cases were compared with all newborns hospitalised for more than 48h in the neonatal intensive care unit (NICU). Cohorting of infected patients and work reorganisation were implemented. Pulsed-field gel electrophoresis was performed. The retrospective cohort included the six cases and 13 control patients that had been in the NICU during April 2006. Univariate analysis showed that the use of dobutamine was significantly associated with infection (P=0.036) and that enteral feeding was a protective factor (P=0.02). Multivariate analysis did not find any independent risk factor. Bed occupancy rate in March 2006 was 109.6%, indicating overcrowding. PFGE identified indistinguishable patterns among isolates from all six newborns. PubMed and OVID was search from 1 January 1983 to 15 January 2008 for papers including the terms 'E. cloacae', 'outbreaks', 'clusters' in combination with 'neonate', 'newborn', and 'infant'. We found 26 reports of outbreaks due to E. cloacae in neonate patients: sixteen (52%) were bloodstream infection outbreaks, of which two (12.5%) were related to multiple-dose medications. The source for our outbreak was not identified. Reinforcement of hygiene practices, restrictions on new admissions and the establishment of single-dose medications helped to control the outbreak.