The ability of rTMS to affect mood was first noted in normal controls in the late 1980's. Studies using focal stimulation of the dorsolateral prefrontal cortex (DLPFC) in depression first appeared in the mid 1990's [9-11]. These studies produced promising results with reduced depression severity following left prefrontal cortex (PFC) stimulation. Since that time a considerable number of trials of left DLPFC rTMS have been conducted. The majority of these studies have used 5-20 Hz stimulation frequency. Most of these have predominately been small in sample size and of short duration (i.e., 10 treatments) (CIA pub 11). They have also been confounded by concerns about the choice of sham stimulation type [12] and variation in stimulation 'dose' provided. The studies with the most robust clinical effects have used a higher number of pulses per subject and higher stimulation intensity levels, suggesting a dose - response relationship (CIA pub 2,11). They have almost exclusively focused on the treatment of patients with unipolar major depression although some of these studies have included a subset of patients with BPAD-DP.