Abdominal Aortic Aneurysm is a dilatation of the aortic artery that occurs in response to degradation of the wall structure. The present research focused on developing a realistic hemodynamic model of the aneurysm using a new method to assign boundary conditions. A three element Windkessel model was coupled to the 3D geometry model of the disease in order to couple inlet flow with outlet pressure. This model resulted in more precise hemodynamic conditions for pulsatile flow: 1- in terms of realistic wall pressure values and pressure curves, 2- realistic geometry effect. Contours of wall shear stress, mean wall shear stress, static pressure, and velocity streamlines were calculated and results were compared for two patients and an ideal geometry of the aneurysm. Finally maps of mean wall shear stress were produced to investigate relationship between values of the mean wall shear stress and histological profiling of aneurysm specimens obtained during surgery.