This study investigated the effectiveness of the Lee Silverman Voice Treatment (LSVT) program on the voice and speech impairments in a 58 yr old woman with Parkinson's disease (PI) following thalamotomy and pallidotomy surgery. Perceptual, acoustic, and physiological assessments of motor speech function were performed prior to and following the LSVT program, and at 6 months post-treatment. Perceptual measures included percentage word and sentence intelligibility, number of intelligible words per minute, and communication efficiency. Acoustic measures included sound pressure level, duration of phonation, percentage voiced, jitter, shimmer, and fundamental frequency. Physiological measures included subglottal pressure, laryngeal resistance, phonatory flow, and number of syllables per breath and per minute. Results demonstrate a marked improvement in the subject's speech intelligibility immediately post-LSVT as reflected by increases in vocal volume, phonatory stability, respiratory-phonatory control, and a decreased rate of speech. At 6 months post-treatment, initial gains in speech intelligibility and respiratory-phonatory control were not maintained, although the S retained the ability to increase phonatory effort and improve vocal function on vowel phonation and reading. The results are discussed in relation to the effectiveness of the LVST for patients with severe hypokinetic dysarthria following stereotactic surgery, and the bases of the subject's inability to maintain long-term effects of treatment.