Repetitive transcranial magnetic stimulation (rTMS) is a comparatively novel option for the treatment of major depressive disorder (MDD) and other psychiatric illnesses. Previous research has shown rTMS to be safe and without significant side effects compared to pharmacologic options. However, rare cases of rTMS-induced mania have been reported. This case report describes such an affective switch in a 52 year old female veteran with treatment-resistant MDD and a history of electroconvulsive therapy (ECT)-induced mania. Six treatments of rTMS were administered at 5 Hz for a total of 3000 pulses per day, when the patient began to display multiple hypomanic symptoms. These symptoms decreased after the termination of treatment and abated within a couple of days. In conclusion, caution should be used when administering rTMS to patients with a history of ECT-induced mania.