A mouse model of aortic endothelium regeneration following mechanical injury was studied in wild-type and apoE-deficient (apoE0) animals. The injury induced a topologically nonuniform and complex reparative response. Compared to wild-type animals, apoE0 mice had unaltered ability to regenerate endothelium. Despite the pro-coagulative state of the apoE0 mice, no arterial thromboses were detected. Only deeper arterial injury with damage to the internal elastic membrane was associated with the development of atherosclerotic lesions in apoE0 mice. During the limited observation period of 7 days, superficial arterial injury in apoE0 mice was inconsequential. In addition, for the first time in vivo, rolling of polymorphonuclear leukocytes over the damaged endothelium was documented.