Experimental studies in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated monkeys have shown that akinesia and rigidity are linked to a hyperactivity of glutamatergic subthalamic nucleus neurons and that the lesion of this nucleus can ameliorate parkinsonian motor signs. In our study, high-frequency stimulation applied at the subthalamic level was performed on two Macaca mulatta monkeys rendered hemiparkinsonian by unilateral infusion of MPTP. Its effects on rigidity and bradykinesia have been quantified. The results exhibit an important alleviation of both symptoms during the application of subthalamic stimulation comparable to that obtained during L-Dopa treatment, but without the appearance of abnormal movements such hemiballism or dyskinesia. Our data show that subthalamic stimulation has a beneficial effect on experimental parkinsonian rigidity and bradykinesia and suggests a new therapy approach for the treatment of Parkinson's disease by using subthalamic high-frequency stimulation instead of L-Dopa treatment.