Objectives：This study evaluated the association between behavioral characteristics and polymorphisms in DAT1, DRD2, DRD3, and DRD4 genes. Methods：The subjects were 114 neonates, who were born by normal spontaneous vaginal delivery and had no physical problems. The behavioral characteristics were evaluated using Neonatal Behavioral Assessment Scale(NBAS) at $17.8{pm}7.0$ hours after their birth to minimize environmental influences, and cord blood was used to analyze the gene polymorphisms. Results：In comparison to DAT1 gene 10/10 genotype group(N=93), other genotype group(N=19) showed significantly high NBAS scores on social-interaction, state organization, and state regulation. DRD2 gene Ser311/Cys311, TaqI A, and TaqI B polymorphisms showed no significant differences on NBAS scores when they were grouped by genotypes. DRD3 gene polymorphism and DRD4 gene promotor polymorphism showed no significant difference on NBAS scores when they were grouped by genotypes. In comparison to the short repeats(N=102), long repeats(N=10) in DRD4 gene showed significantly high habituation score of NBAS. Conclusion：These results suggest that the genetic effects of the neonatal behavioral characteristics may be mediated via DAT1 and DRD4 genes.