The purpose of this study was to assess several acoustic features of the voices of 26 parkinsonian patients under two conditions, with and without bilateral chronic stimulation of the subthalamic nucleus (STN) to estimate the effectiveness of this procedure on parkinsonian speech. When compared to unstimulated patients, stimulated patients showed longer duration of sustained vowels, shorter duration of sentences, nonsense words, and pauses, more variable fundamental frequency (f0) in sentences, and more stable f 0 during sustained vowels. Relative intensity was unchanged in both conditions. Further acoustic analyses are warranted to clarify the role of STN stimulation on parkinsonian speech.