We report the results of a single-subject multiple baseline across behaviours experiment of a 74-year-old woman presenting with Parkinson's disease. Her speech was typical of a hypokinetic dysarthria. The main features of her dysarthric speech were: a restriction in the modulation of fundamental frequency, an inappropriate pitch level and a rate disturbance. Three measures of prosody were operationally defined as follows: (1) linguistic modulation of fundamental frequency, (2) mean fundamental frequency and (3) rate. Treatment focused on ameliorating these aspects employing a multiple baseline design. Measures during and post-therapy documented improvement for each of these aspects of prosody. Independent judges were also more capable of understanding her speech and her speech prosody after therapy. Upon follow-up measures 10 weeks later, most of the improvement was maintained.