Purpose: The characteristics of hospitalized patients in neonatal intensive care units (NICUs), including hospitalization costs (HC) and National Health Insurance (NHI) status were studied. Methods: We gathered the following data from 7 hospitals in Korea during 2006: the distribution of patients according to birth weight (BW), and the duration of the hospital stay according to BW and He. Results: The patients who were admitted to the NICU consisted of high-risk neonates, including low birth weight or premature neonates, which comprised 50% of all neonates admitted to the NICU. The duration of hospitalization was 75-90 days for neonates with BW <1,000 g, 45-60 days for neonates with BW between 1,000 and 1,499 g, and approximately 15 days for neonates with BW between 2,000 and 2,499 g. The portion of the HC covered by the NHI was 77.1%, 22.9% of the total HC was not covered by the NHI (19.5% was included in the list, but not covered by the NHI and 3.4% was not listed, but covered by the NHI). The average total HC per person was 4,360,000 won, and the HC covered and not covered by the NHI were 3,677,000 won and 1,007,000 won, respectively. The mean HC were as follows; 35,000,000 won for a BW <500 g, 18,000,000 won for a BW between 500 and 999 g, 16,000,000 won for a BW between 1,000 and 1,499 g, and 4,200,000 won for a BW between 1,500 and 1,999 g. Conclusion: Not only premature, but also ill neonates were under the care of the NICU. The HC increased as the BW decreased and the hospitalization period increased. The proportion of the patient's financial burden is >25% of the total He. For this matter, additional NHI is needed.