Initial therapy of a patient newly diagnosed with Parkinson's disease depends on a variety of presenting symptoms and therefore must be individualized. Some patients do not initially require any therapy or can be managed with small doses of antidepressants. Anticholinergics are useful initial drugs for some patients, particularly when tremor is a presenting symptom. For rigidity, levodopa is the drug most likely to be helpful. Dopamine agonists and amantadine may be used initially, but more often are used as adjunct therapy later in the course of the disease. Selegiline probably should be considered for all newly diagnosed patients, because it may have the potential to slow disease progression.