The differential diagnosis of PD includes other neurodegenerative disorders; hereditary disorders; and symptomatic causes, such as structural lesions, infections, metabolic abnormalities, hydrocephalus, and drugs or toxins. A good history of symptom evaluation, drug use, and family illness is just as essential as a careful neurologic examination when evaluating a patient with parkinsonism. Although there is no definitive diagnostic test for PD at this time, tests to rule out other causes should be considered and then treatment started.