It has been shown that a functional promoter dinucleotide repeat length variation of the neuronal nitric oxide synthase gene (NOS1 Ex1f-VNTR) is associated with impulsivity-related behavioral phenotypes. In this study, the Eysenck Impulsivity Questionnaire (IVE-7) was administered to 182 male offenders to prove the hypothesis that NOS1 Ex1f-VNTR is associated with self-reported impulsiveness, venturesomeness and empathy. Multivariate analysis of variance (MANCOVA) revealed a significant multivariate effect of NOS1 Ex1f-VNTR genotype on IVE-7 measures (P = 0.0006). The effect was more pronounced regarding impulsiveness and empathy (P = 0.0052 and P = 0.0036, respectively) as compared with venturesomeness, which was only of borderline significance. The findings give additional evidence that NOS-I is involved in the regulation of impulsive personality traits and support the notion that the NOS1 gene takes part in the regulation of social behavior.