New concepts about the pathogenesis and pathophysiology of Parkinson's disease have emerged. For these concepts to be useful, they must be understood, and for them to be applied, the psychology of the patient and the patient's family must be understood. The initial consultation is crucial in establishing a successful relationship between a patient, family, and physician. This consultation is analyzed and ways of avoiding errors and misconceptions delineated. Emphasis is placed on imaginitive questioning using the format of the ADL portion of the UPDRS in establishing the diagnosis and following treatment. The rational for starting treatment with selegiline at this time is discussed in the context of the role that increased MAO-B activity plays in the progression of Parkinson's disease. After making the diagnosis and starting treatment with selegiline, deciding when to start levodopa is the next crucial decision. Often as important as deciding when to start levodopa is overcoming the resistance of the patient to accept this treatment. The next crucial decision occurs after the patient develops response fluctuations on levodopa. A format for assessing the fluctuations is presented, and the merits of different treatments, including selegiline, dopamine agonists (bromocriptine and pergolide), and sustained-release or controlled-release levodopa preparations (Sinemet CR), discussed. The management of patients with depression, sleep problems, and advanced disease including postural instability and mental changes are reviewed.