Effects of magnetic fields on bainitic transformation temperature, transformation behavior and transformed structures in Fe-based alloys are reviewed, and compared with corresponding effects on ferrite, pearlite and martensite. Bainitic transformation start temperature is increased and the transformation behavior is accelerated by applying magnetic fields. A magnetic field of 10 T is much more effective than the applied stress of 172 MPa for the acceleration of bainitic transformation. No magnetic effect on the transformed structure was observed so far except that the volume fraction of bainite is much larger in magnetic fields.