In this study, we investigated the association between dopamine receptor D4 (DRD4) exon III polymorphism and novelty seeking in 69 Japanese women. The group of subjects with long allele (> or =5 repeats) exhibited significantly elevated novelty seeking scores in comparison with subjects lacking the long allele. By contrast, the scores for harm avoidance, reward dependence, and persistence were statistically indistinguishable in the two group of subjects. With regard to the subscales of novelty seeking, the scores for exploratory excitability and extravagance were significantly higher in subjects with the long allele than in subjects lacking the long allele. However, no significant associations with impulsiveness or disorderliness were recognized. Our results suggest that although long alleles of the polymorphic exon III repeats are low in the Japanese population, there is an association between long alleles of DRD4 exon III polymorphism and novelty seeking.