Transcranial magnetic stimulation is the noninvasive application of localized pulsed magnetic field to the surface of the skull, to cause a depolarization of neurons in the underlying cerebral cortex (Daryl E., Bohning PH.D.). Based on Reciprocal Induction (Faraday, 1831), and the Ampere Maxwell Law, according to which electric energy is associated with magnetic energy and vice versa, transcranial magnetic stimulation has been used during the last fifteen years in the diagnosis of Central Nervous System dysfunctions, its safeness and good tolerance having been proven. Since 1876, when Dàrsonval discovered that the use of a similar apparatus caused vertigo, phosphenes and fainting, thousands of transcranial magnetic stimulation studies have been carried out in the fields of Neurology and Psychiatry. The present is a review of clinical studies carried out in Psychiatry, specifically related to Mood Disorders, Obsessive-Compulsive Disorder and Post traumatic-Stress Syndrome.