Despite the bilateral appendicular symptoms of Parkinson's disease, bilateral surgical interventions in the basal ganglia have been shunned because of cognitive and speech disturbances following bilateral thalamotomy. However, we present the uncomplicated results of 25 simultaneous posteroventral pallidotomies and compare their obvious superior control of appendicular symptoms as well as axial symptoms with the results of 25 unilateral posteroventral pallidotomies.