Management of Parkinson's disease (PD) depends primarily on oral medication. There are several drug classes and multiple doses and formulations, which make optimizing therapy complex. Variable drug absorption and the short half-life of most antiparkinson treatments, especially levodopa, are a main focus in understanding complications and have encouraged alternative delivery systems to limit fluctuation and dyskinesia at later stages. Comparatively little attention is paid to the way patients take their oral medication. Variable medicine-taking behavior can affect the clinician's understanding of the diagnosis and rate of progression, and further prescription of PD medication. Medicine overuse in later stage PD is well documented and causes psychiatric disturbance and increases motor complications, but evidence of undertreatment and erratic intake is emerging, which is likely to affect motor control and quality of life adversely. Methods of quantifying compliance are compared for accuracy and limitations. Understanding medicine-taking behavior is a first step in optimizing therapy and requires consideration of a patient's personal beliefs about their medicines. Although the benefits of regularizing oral medicine-taking in a practical, achievable way in PD remain untested, such an approach might prolong and smooth the benefits of oral medication and is worthy of further research.