Computation fluid dynamics (CFD) is widely used to simulate blood flow in vascular systems. Most of the studies focus on identification of reasons behind the cardiovascular disorders. In this study, magnetic resonance angiography data belonging to a patient were used to obtain brain vasculature solid model. This model prior to CFD simulations was evaluated in terms of surface quality and critical region was identified to be investigated. After CFD analysis, the regions with low and high velocity vector fields, pressure, contours and wall shear stresses (WSS) were obtained. The effect of shape and orientation of vessels was observed. It was seen that increased blood velocity increases the pressure and WSS especially in narrow regions.