This study presents data on the antemortem evaluations of a cohort of individuals registered in a brain donation program. Clinical evaluation determined that many individuals were unaware they had clinical signs of Parkinson's disease (PD) (rest tremor, bradykinesia, rigidity). Quantitative motor testing (timed tapping test and Purdue pegboard test) revealed a graded reduction in performance in those clinically found to have clinically possible and clinically probable PD. Longitudinal examinations over 4 years revealed some individuals progressed from control to clinically possible PD and clinically possible PD to clinically probable PD. This study underscores the importance of longitudinal antemortem testing of prospective brain donors as well as the potential value of quantitative motor testing.