PURPOSE: To determine the incidence, characteristics and outcomes of newborns with congenital heart disease (CHD) developed necrotizing enterocolitis (NEC), and to find various risk factors leading into NEC among newborns with CHD. METHODS: Cardiac diagnosis, age at admission were analyzed for NEC among 508 patients with CHD during January 1997 to December 2002 at Asan Medical Center. Retrospective case control study was undertaken by comparing various demographic variables between those newborns developed NEC and control newborns with CHD did not develop NEC during hospitalization. RESULTS: The incidence of all stages of NEC among newborns with CHD was 6.3%. 25% of those newborns who developed NEC had CHD. The mean gestational age, birth weight for NEC and control groups were 37.7+/-3.5 weeks, 2, 560+/-700 g and 37.6+/-2.3 weeks, 2600+/-1200 g respectively. The severity of NEC, in order, according to Modified Bell's Criteria revealed stage IB (35%) followed by stage 1A (26%), stage IIB (18%), stage IIA (9%), IIIA (9%), and IIIB (3%). The mortality in NEC group was 5/23 (21.7 %). Potential risk factors associated with developement of NEC among newborns with CHD included failure to make prenatal diagnosis of CHD, perinatal complications, requirement of Prostaglandin E1, anemia, sepsis and increased incidence of hemodynamic instability as evidenced by low cardiac output and increased desaturations. Of 23 newborns who developed NEC, excluding 9 premature infants with PDA, 55% had acynotic CHD compared to 45% cyanotic heart disease. CONCLUSION: Awareness of increased risk of NEC among newborns with CHD especially those with potential risk factors is essential to improve their outcomes.