We evaluated motor function in 41 consecutive PD patients undergoing unilateral MRI/microelectrode-guided posteroventral pallidotomy to determine whether the motor effects of levodopa therapy change after surgery. Total Unified Parkinson's Disease Rating Scale motor "off" and motor "on" subscores all improved and the rapidity of action, magnitude, and duration of motor response to levodopa therapy were all maintained after pallidotomy.