Abstract INTRODUCTION Stimulation frequency has been considered a crucial determinant of efficacy in deep brain stimulation (DBS). DBS at frequencies over 250 Hz is not currently employed and consensus in the field suggests that higher frequencies are not clinically effective. With the recent demonstration of clinically effective ultrahigh frequency (UHF) spinal cord stimulation at 10 kHz we tested whether UHF stimulation could also be clinically useful in movement disorder patients with DBS. We evaluated the clinical effects and safety of UHF DBS in patients with subthalamic nucleus (STN) or ventral intermediate thalamic nucleus (VIM) DBS. METHODS We studied the effects of conventional (130 Hz) and UHF stimulation in 5 patients with Parkinson's disease (PD) with STN DBS and in one patient with essential tremor (ET) with VIM DBS. We compared the clinical benefit and adverse effects of stimulation at various amplitudes either intraoperatively or postoperatively with the electrodes externalized. RESULTS Motor performance improved in all 6 patients with UHF DBS. About 10 kHz stimulation at amplitudes = 3.0 mA appeared to be as effective as 130 Hz in improving motor symptoms (46.2% vs 53.5% motor score reduction, P = .110, N = 90 trials). Interestingly, 10 kHz stimulation resulted in fewer stimulation-induced paresthesiae and speech adverse effects than 130 Hz stimulation. CONCLUSION Our results indicate that DBS at 10 kHz produces clinical benefits in patients with movement disorders. Like 10 kHz spinal cord stimulation, 10 kHz DBS has the potential to produce clinical benefits while possibly reducing stimulation-induced adverse effects. Further studies will be required to optimize UHF DBS stimulation parameters and to determine its clinical utility.