Background. Personality traits have shown considerable heritable components. Association between alleles of a polymorphism in the third exon of the dopamine D4 receptor gene (DRD4) and the personality trait Novelty Seeking has been reported. Recently, in a sample of Swedish non-psychiatric subjects we could not detect any significant relationships between the same polymorphism and Novelty Seeking related scales in the Karolinska Scales of Personality (KSP). However, there was a tendency in the direction of the proposed association. There were also tentative associations between an exon I 13 bp deletion polymorphism and the personality traits Socialization and Guilt.Methods. We investigated a new Swedish population-based sample (N=167) investigated with the KSP for three DRD4 polymorphisms.Results. Neither of the previous results were replicated. Combining the previous and the present samples did not give rise to any significant association between DRD4 polymorphisms and personality scales.Conclusions. The dopamine D4 receptor gene is probably not of importance to the different personality dimensions as measured by the Karolinska Scales of Personality.