PURPOSE: Enterobacter is one of the important organisms in neonatal intensive care unit. We reviewed the clinical characteristics, underlying diseases, invasive procedures during admission, mortality and antibiotic sensitivity of Enterobacter infection in NICU. METHODS: We retrospectively reviewed 21 neonatal patients whose blood cultures yielded Enterobacter between June 1994 and June 1997 at Dongguk University Hospital. RESULTS: Blood cultures were positive in 62 from 2,025 neonates and 21 was Enterobacter. The clinical spectrums were diverse such as sepsis (85%), pneumonia, disseminated intravascular coagulopathy and necrotizing enterocolitis. The underlying conditions upon admission were composed of prematurity (38%), hyaline membrane disease (38%), jaundice, sepsis and pneumonia. The procedures used during admission were endotracheal intubation (57%), mechanical ventilation (57%), umbilical vessel catheterization, gastric tube inserition, total parenteral nutrition and exchange transfusion. The antibiotic sensitivity was as follows : ampicillin (0%), ceftriaxone (0%), amikacin (55%), gentamicin (85%), ciprofloxacin (100%), imipenem (100%). Overall mortality was 26.5%. Mortality was significantly high in cases of leukopenia (P< or = 0.01), thrombocytopenia (P< or = 0.01) and use of inappropriate antibiotics (P< or = 0.01). CONCLUSION: Enterobacter is an important organism in the cause of nosocomial infection in NICU and has a high rate of mortality. Enterobacter infection was associated with prolonged hospitalization, invasive procedures and preceding antibiotics. Commonly used antibiotics such as penicillin and cephalosporin would be inappropriate for the treatment of Enterobacter infection. We consider the use of gentamicin or imipenem to be far more effective in the initial therapy of Enterobacter infection.