Transcranial magnetic stimulation (TMS) is a relatively noninvasive technique to interfere with the function of small cortical areas through currents induced by alternating magnetic fields emanating from a handheld coil placed directly above the targeted area. This technique has clear effects on a whole range of measures of brain function and has become an important research tool in neuropsychiatry. More recently, TMS has been studied in psychiatry mainly to assess its putative therapeutic effects in treatment refractory major depression. Most studies indicate that both low-frequency TMS and higher (20 Hz) frequency repetitive TMS may have some antidepressant properties. However, definite therapeutic effects of clinical significance still remain to be demonstrated.