Parkinson's disease for <5 years, non-demented, no or <6 months of levodopa and none during trial. Off levodopa, DA agonists, and psychotropics for 30 days before screening. Amantadine, anticholinergics allowed if at stable dosage. Hoehn & Yahr stage I-III. Depression allowed, but no other chronic disease that is unstable or might interfere with ability to participate.