In this paper pulsatile laminar blood flow in an axisymmetric stenosed tube is simulated by the Non-Newtonian Power law model. Effect of stenosis, for severe condition of 75% reduction of local area was considered and the flow patterns for three Womersley numbers were studied. The results show that there is a fundamental difference in the flow pattern at . This difference is related to second co-rotating vortex which is observed downstream of stenosis at . The propagation of disturbance that leads to formation of this vortex is shown by wall shear stress surface at . Examining three flow patterns shows that the time that primary vortex forms on the distal face of stenosis is delayed with increasing Womersley number