The steady slip flow assuming blood as the Casson fluid has been studied under the influence of transverse magnetic field. The results for the axial velocity, plug flow velocity, flow flux and the wall shear stress have been analyzed analytically and graphically taking suitable parameters. The analysis shows that the axial velocity, plug flow velocity and the flow flux increase along axial distance as the pressure gradient, magnetic field gradient and slip velocity increase but they decrease when the stenosis height increases. Also the wall shear stress showing fluctuations increase in z