PURPOSE: The purpose of this study is to compare the clinical characteristics and predisposing factors of necrotizing enterocolitis (NEC), primarily a disease of the premature, in between term and preterm groups. METHODS: We retrospectively reviewed the medical records of 36 neonates with NEC (> or =modified Bell's staging criteria IIa) who were admitted to the NICU of Seoul National University Children's Hospital from January 1, 2000 through December 31, 2004. 20 full and 16 preterm neonates were compared in regard to demographics, clinical characteristics and predisposing factors. RESULTS: 29/36 neonates(80.6%) were outborn. Mean gestational age and birth weight were 38.5+/-0.9 weeks and 3, 010+/-490 g, term and 31.4+/-3.4 weeks and 1, 460+/-750 g, in preterm respectively group. Mean age at diagnosis was 17.3+/-13.5 days in term versus 20.8+/-19.6 days in preterm group. Abdominal distension was the most common finding in both groups and diarrhea was significantly more common in term group. Congenital heart disease, intrauterine growth retardation, bacterial infection were found in 75.0% of term group. The rates of surgical intervention and complication were higher in preterms, however, mortality rate was higher in term group. Congenital heart disease, especially the presence of complex heart disease with poor systemic perfusion or heart failure, was associated with higher mortality. CONCLUSION: Diarrhea was more common in term group. Neonates with predisposing factors for NEC, especially in term neonates with congenital heart disease, should be followed closely for early diagnosis and proper treatment.