International audience; The cardiovascular pathologies are the first cause of mortality in the world. The constant research on the understanding, prevention, therapy improvement and the prostheses development to fight against these cardiovascular diseases is therefore not incidental. The multifactorial nature of these diseases involves a diversity and a transversal approach. Thus, various members of the community are trying to combine their research, not only on the initiators mechanisms of these diseases but also to propose, among other things, better criteria for clinical diagnosis and better treatment therapies. To achieve these goals, biomechanics, in collaboration with clinicians, are trying to develop models close to the physio-pathological reality. These models, (in vivo, in vitro and numerical) simulate blood flow in different singularities of the cardiovascular system. Thus, based on fundamental studies on the normal physiological and pathological flow hemodynamic in realistic geometrical models it is possible to undertake applied work to assist clinicians and to optimize prostheses. This work will illustrate this approach by concrete examples in cardiac and vascular biomechanics. Two clinical issues will be addressed: the abdominal aortic aneurysms (AAA), the coronary re-stenosis caused by the implantation of coronary stents.