In just 12 years since its introduction, deep brain stimulation (OBS) has become well established as a safe - and effective therapy in the treatment of medically refractory movement disorders. Ventralis intermedius (Vim) OBS has virtually replaced thalamotomy in the routine clinical treatment ofessential tremor, affording relief to thousands of patients who previously would not have undergone surgery, and there is increasing usage of Vim DBS in other tremors of intention (e.g., multiple sclerosis). Subthalamic nucleus (STN) and globus pallidus internus (GPO DBS have revolutionized the treatment of advanced stage Parkinsonls disease, improving all cardinal disease features and increasing lon l time without dyskinesias. Finally, DBS of various sub-cortical structures is being developed and tested in other less prevalent movement disorders such as dystonia. Future developments in this rapidly advancing area will no doubt include widening indications for this relatively safe surgical procedure, elucidation of the mechanisms of action of electrical stimulation, and technological advancements improving effectiveness and convenience. [Neural Res 2000; 22: 247-258]