The authors of this paper view Parkinson's disease (PD) as a clinically defined progressive syndrome of resting limb tremor, bradykinesia, muscle rigidity, and a shuffling unsteady gait that responds well to dopaminergic medications. Parkinson's disease is a not a single entity, but rather a syndrome with diverse causes, with both genetic and environmental risk factors. The clinician's concern is to rule out other entities, especially those having another specific treatment, and to give PD patients the best short- and long-term benefit, with the least possible unwanted side effects.