PURPOSE: Malnutrition and failure to thrive have long been recognized as common systemic consequences of congenital heart disease(CHD). But there is little data about the prevalence and severity of malnutrition with CHD in Korea. We designed this study to determine the prevalence of malnutrition among hospitalized children with CHD. METHODS: We reviewed 100 hospitalized children with CHD who were randomly selected from consecutive admissions at department of pediatrics and thoracic surgery of Asan Medical Center from Jul. 1998 to Jun. 1999. A cross-sectional, retrospective study was done. Acute malnutrition was determined by calculating a ratio of the children's weight to the mean weight for the children's height. Chronic malnutrition was assessed by obtaining a ratio of the children's height to the mean height for the children's age. According to these criteria, malnutrition is divided into mild, moderate, and severe categories. RESULTS: Acute and chronic malnutrition occurred in 39% and 31% of the children, respectively. Age, diagnosis, and symptoms were analysed with the presence of the malnutrition. Forty nine percent of infants diagnosed as suffering from acute malnutrition, and cyanosis appear to be the ones the most severely important factor(P<0.001). Cyanotic children with pulmonary hypertension are the ones most severely affected(P<0.001). Acute or chronic malnutrition occurred in more than 44% of children with cyanosis and/or congestive heart failure but in only 11% of children with neither(P<0.001). CONCLUSION: Malnutrition in CHD is relatively high. We suggest nutritional screening and intervention for the children with CHD should be considered.