This is a multi-center, open-label study of short-term treatment with levodopa or cabergoline on striatal DATscan uptake in early Parkinson's disease. Approximately 120 Parkinson's disease subjects will be randomized to receive either carbidopa/levodopa, cabergoline or no treatment during a twelve week period. Subjects will undergo SPECT imaging with DATscan at screening and after 12 weeks. After twelve weeks carbidopa/levodopa and cabergoline treatment will be withdrawn and all subjects will undergo SPECT imaging with DATscan after 8 weeks (20 weeks after baseline).