The purposes of this study were: (1) to determine whether there was a correlation between a quantitative assessment of postural sway , and a clinical assessment of postural stability, in patients diagnosed with idiopathic Parkinson's disease (PD); (2) to plot individual diurnal changes in postural sway characteristics of PD patients over an eight-hour time period; (3) to plot day to day changes in individual postural sway characteristics of PD patients: (4) to determine whether there was a difference in the postural sway characteristics of parkinsonians, with and without vision; (5) to determine whether there was a difference in the postural sway characteristics of the same individuals when using either Sinemet or Oeprenyl. Three male PD patients were recruited into this study. Each subject stood on a stable force platform (AMT1 OR6-5-1). Measurements included the standard deviations of the coordinates of the centre of pressure (COP) in the anterior-posterior (a-p) and lateral (lat) directions, the mean velocity of sway, and area of sway. These dependent measures were evaluated in a "quiet standing" condition, once with the eyes open (EO) and once with the eyes closed (EC). These procedures were carried out ten times over the course of an eight hour day. Each subject was tested two days while taking eight hour day. Each subject was tested two days while taking Sinemet, and two days while on the Deprenyl regimen. Secondly, at two periods of each test day, each patient was evaluated using the postural assessment section of the Sears Parkinson's Assessment Form (SPAF). The results were: (1) group analyses and individual analyses established the evidence of significant correlations between both the quantitative measures of postural sway (force platform) and the qualitative assessment tool (SPAF): (2) significant variability was evident in the analysis of individual data plots: (3) no statistically significant differences were observed tor any subject when measured from day to day; (4) generally, vision was a stabilizing factor in postural control, however, this was quite variable for each subject; (5) significant improvements in postural stability were observed with the introduction of Deprenyl for one out of three subjects. These findings are discussed in terms of their clinical and behavioral importance, with specific reference to Physiotherapy. / Thesis / Master of Science (MS)