Setting and Subjects: Subjects for this study will be idiopathic Parkinson's disease patients identified from the Oregon Health & Science University movement disorder clinic as candidates for deep brain stimulation therapy. Enrollment will continue until fifty subjects have been implanted with electrodes using frameless stereotaxis and intraoperative CT. Data regarding quality of life, motor control, and amount of time during the day without levodopa side effects will be collected pre-operatively and post-operatively. This data will be compared to historical controls who have been implanted with DBS electrodes using MER and frame-based stereotaxis. All surgical procedures will involve only Federal Drug Administration (FDA) approved stereotactic equipment, used in the manner for which they have been approved. All clinic procedures are standard of care for movement disorders patients in the deep brain stimulation program.