Purpose: Since 1997, private postnatal care facilities (San-hu-jo-ri-won in Korean) have emerged to take the role of the family. As a result, neonates are now exposed to many people and are very vulnerable to infection. However, there has been no study on the influence of postnatal care facilities on neonatal infection. The aim of this study was to determine the risk factors of neonatal infection in fullterm babies in Korea. Materials and Methods: We followed up 556 pregnant women and their babies for 4 weeks after their births at 2 hospitals in Seoul and Daejeon from October 2004 to September 2005. Among 512 full-term babies, 58 had infectious diseases. To determine the risk factors for infection, 53 infected neonates at 4 - 28 days of life and 413 healthy neonates were compared. Results: The incidence of neonatal infection at 4 to 28 days after birth was 10.5%. After adjusting the related factors, the number of siblings (OR = 2.05, 95% CI = 1.13 - 3.71 for 1 or more) and postnatal care facilities or home aides (OR = 1.91, 95% CI = 1.07- 3.45) were significant risk factors. Formula or mixed feeding (OR = 1.66, 95% CI = 0.91 - 3.04) increased the risk of neonatal infection but it was not statistically significant. Conclusion: When the newborns had siblings, stayed at postnatal care facilities, or were cared for by home aides, the risk of neonatal infections significantly increased. Further research on the feeding effect on neonatal infection and evaluation of prevention efforts are needed.