Magnetic field applying is one of the novelist methods for heat transfer enhancement. In the present study the most recent studies about the effects of magnetic field on the heat transfer performance of different systems is studied and the results of them are evaluated and compared with other heat transfer improving techniques. The results of studies indicated the completely different results of magnetic field effects at different condition. Applying the magnetic field on systems with respect to the kind of fluid, heat transfer condition (natural, forced convection and thermosyphon), the kind and side of magnetic field and the equipment may cause to increment, decrement or stopping the heat transfer and also in some cases maybe have not any considerable effect on the heat transfer rate of the system.