The therapy with pulsed electromagnetic fields (PEF's) has been used as a therapeutic modality for at least 40 years. One of its well acknowledged uses is the healing of non-union fractures, [5] although there are other medical conditions that have also been susceptible to be treated with this type of therapies, like migraine [6], Parkinson disease, [7] and epilepsia, [8] among others. Nevertheless, only a few published studies demonstrate the effectiveness of the PEF's in the handling of migraine. These studies have been carried out in a small number of patients, without control groups6 or for very short periods of time [6, 9] as to demonstrate a suitable prophylactic effect. Therefore, this placebo-controlled, double-blind, crossed clinical study was carried out in order to evaluate the prophylactic effectiveness of the therapy with PEF's in the handling of migraine.