Purpose: We studied the influence of the genetic background and age on the vascular injury response in a murine femoral artery injury model. Methods: A femoral artery injury (electrical current) was performed on young mice at the age of 6 weeks and on old mice at the age of 4-8 months of both, the 129 mouse strain and the DBA strain. The mice were allowed to recover for 3 weeks and then perfusion fixed for histologic and morphometric analysis of a mid-lesion section. Results: For both mouse strains the non-instrumented right femoral artery revealed comparable vessel dimensions. In contrast, following application of the electrical current the young mice of the 129 strain (n=14) showed a significantly (p<0.05) enhanced neointima formation compared with young mice of the DBA strain (n=12). The values are given in the table. The 8.3-fold increase in neointima formation resulted in a 1.4-fold increase in the cross-sectional vessel wall area for the 129 strain compared with DBA. For older mice with corresponding bigger vessels we found less injury response in both strains, but it was still a weak trend (p=0.14) for an increased neointima in the 129 strain (n=8) versus the DBA strain (n=9). Conclusions: Vascular injury response in our model is not considerably dependent on the age of the animals, but is primarily controlled by the genetic pattern of the mice. Serial testing of various mouse strains with regard to their genetic differences will provide candidate genes for the control of vascular injury response.