• Change from baseline in UPDRS (Unified Parkinson's Disease Rating Scale) II + III total scores at end of maintenance, for sumanirole compared to placebo
  

• To assess the safety profile of sumanirole; the benefit of sumanirole in quality of life measures, and change from baseline in UPDRS II + III total scores at end of maintenance, for sumanirole compared to ropinirole
  

Inclusion Criteria:

Parkinson's disease of less than 7 years duration

Modified Hoehn and Yahr Scale Stages 1 through 3.

Age greater than or equal to 30 years old.

Men or women (women of childbearing potential must have a negative pregnancy test at screen) and both must use adequate contraceptive methods.

Patients who are willing and able to comply with scheduled visits, treatment plan, laboratory tests, and other study procedures.

Exclusion Criteria:

Atypical Parkinson's disease syndromes due to drugs, metabolic disorders, encephalitis, or degenerative diseases.

Levodopa received for 1-year accumulated interval in the last two years.

Dopamine agonist medications or catechol-o-methyl transferase inhibitors in the 30 days prior to baseline.

Unstable dose regimes of hypnotics, anxiolytics or antidepressants

Dementia

History of stereotaxic brain surgery, psychosis or active epilepsy within past year.

Participation in clinical trial within the previous 30 days.

Malignant melanoma or history of melanoma

Significant medical or pshychiatric condition.