The three-dimensional computational model of a simplified saccular brain aneurysm is used to study the time-dependent hemodynamics under the effect of an external magnetic field.The model takes into account the Non-Newtonian behavior of the blood to compute the velocity field and wall shear stress (WSS).The intensity of the magnetic field is varied so as to evaluate its effect on the velocity and WSS.Results at systole phase (0.18 s) show that under the action of an applied external uniform magnetic field, the velocity of the blood flow decreases while the temporal variation of WSS increases in the neck of the aneurysm.In addition, flow is redirected to the bulge creating a stagnant fluid at the aneurysm neck.