Study for patients currently using Levodopa/Carbidopa who will be assigned to receive either Rasagiline or Placebo

Inclusion Criteria:

Men and women with idiopathic Parkinson's disease whose diagnosis is confirmed by at least two of the cardinal signs (resting tremor, bradykinesia, rigidity) being present, without any other known or suspected cause of parkinsonism.

Subjects must experience levodopa related motor fluctuations averaging at least 2.5 hours daily in the OFF state.

Subjects must be taking optimized levodopa/carbidopa or levodopa /benserazide carbidopa/levodopa therapy (based on investigator's judgment), stable for at least 14 days prior to baseline. Subjects must be receiving at least 3 daily doses of levodopa, not including a bedtime dose.

Selegiline must be discontinued for at least 90 days prior to baseline.

Subject must be age 30 or older.

Subjects must be willing and able to give informed consent.

Exclusion Criteria:

Subjects with a clinically significant or unstable medical or surgical condition which would preclude safe and complete study participation. Such conditions may include cardiovascular, pulmonary, hepatic, renal, or metabolic diseases or malignancies as determined by medical history, physical exam, laboratory tests, chest x-ray, or ECG for Parkinson's disease [e.g., pallidotomy, thalamotomy, and deep brain stimulation (DBS)] within the 12 months preceding the Baseline visit.

Subjects who have undergone neurosurgical transplantation are excluded regardless of when the procedure(s) was performed. No programming changes are permitted in subjects who have undergone DBS.

Participation in a previous clinical trial of rasagiline. Concomitant therapy with MAO inhibitors, reserpine, methyldopa within the past three months, or treatment with an anti-emetic or neuroleptic medication with central dopamine antagonist activity with the past six months.