The mechanics and fatigue of stents in the arterial system due to body motion is of vital importance to the use of stents in treating cardiovascular disease. Muscle tension and joint flexure results in stretching, bending, twisting, and compressive flattening of the arterial vessels in the muscles in adjacent regions. If stenotic vessels in these regions are treated with vascular stents, then the stents will also be subjected to these forces. Direct and indirect measurements of arterial deformations have been made in-vivo and will be presented. Fatigue tests based on these deformations are being used to test new stent designs for challenging vessels as the femoral and carotid arteries.