This study aims at characterizing and modelling the effect of mechanical factors on endothelial denudation during angioplasty, such as normal force between balloon and artery, stretching of arterial walls, and relative displacement between contacting surfaces. Friction damage was applied to porcine aorta samples with different contact forces, relative displacements, and biplanar stretching conditions. After the tests, endothelium denudation was quantified by isolating and counting the remaining endothelial cells. Using multiple-regression analysis, a constitutive model is proposed for integration in finite element software. This model will help optimize balloon and stent deployment conditions to minimize the amount of damage to the endothelium, and eventually to reduce the occurrence of restenosis.