The recent progress in the basic knowledge of basal ganglia pathways and advances in the techniques of the neuroimaging studies enabled subthalamic deep brain stimulation (STN DBS). In Korea, more than three hundreds and fifty patients with PD have been treated with STN DBS since the first trial at March 2000. STN DBS effectively improves all parkinsonian deficits occurring especially during levodopa 'off' period and decreases the daily 'off' time. The daily requirement of levodopa dosage can be reduced to about half of the preoperative one. The favorable responses to the STN DBS can be maintained even after five years. However, parkinsonian deficits during levodopa 'on' period can not be controlled as effectively as those during the levodopa 'off' period. The axial symptoms including gait disturbance and postural instability during the levodopa 'on' period cannot be improved or even are worsen by STN DBS. Patients aged over 70 frequently show less remarkable improvement of parkinsonian deficits than the younger ones. Therefore, selection of appropriate candidate for STN DBS is the most important factor deciding the outcome of the STN DBS.