Deep brain stimulation has emerged rapidly as an effective therapy for movement disorders. Deep brain stimulation includes an implanted brain electrode and a pacemaker-like implanted pulse generator. The clinical application of deep brain stimulation proceeded in the absence of clear understandings of its mechanisms of action or extensive preclinical studies of safety and efficacy. Post mortem studies suggest that there is a loss of neurons in proximity to the active electrode, but the resulting lesions are not sufficient to treat the disorder and efficacy requires continued stimulation. Overall complication rates can exceed 25%, and permanent neurologic sequelae result in 4-6% of cases. As the application of deep brain stimulation expands, it is critical to understand the origin of adverse events and the delivery of nondamaging stimulation.