The purpose of this study is to show that higher minimum concentration values are obtained following repeated doses of Stalevo 4 times daily compared to lecodopa/carbidopa treatment with corresponding dosing regimen.

Inclusion Criteria:

• Written informed consent obtained
• Male or female patients with idiopathic Parkinson's disease with either a stable drug response or mild and predictable end-of-dose wearing-off symptoms.
• Hoehn and Yahr stage 1-2.5 performed during the "ON" state.
• Treatment with 3-5 daily doses of levodopa/DDCI ± entacapone with a total daily levodopa dose in the range of 300-600 mg.
• Unchanged levodopa/DDCI ± entacapone and other antiparkinsonian medication (dopamine agonists, monoamine oxidase B (MAO-B) inhibitor, amantadine and/or anticholinergics with doses recommended by the manufacturer), if any, for at least 2 weeks prior to the first treatment period.
• Age within 30-72 years, inclusive.

Exclusion Criteria:

• Secondary or atypical parkinsonism.
• Patients with moderate to marked wearing-off symptoms or any unpredictable "OFF"-periods.
• Patients with treatment-related peak-dose dyskinesia.
• Change in dose strength, daily dose or dosing frequency of any medicinal products used to treat other medical conditions than Parkinson's disease within 2 weeks.
• Use of any iron preparations or other chelating agents.
• Patients with a history of a laboratory abnormality consistent with, or clinically significant cardiovascular, pulmonary, gastrointestinal, hepatic, renal, neurological or psychiatric disorder or any other major concurrent illness, which may influence the outcome of the study.
• History of neuroleptic malignant syndrome (NMS) and/or non-traumatic rhabdomyolysis, malignant melanoma, narrow-angle glaucoma or pheochromocytoma.
• Any abnormalities in laboratory values, vital signs or electrocardiogram (ECG) with clinical relevance.
• Patients using any antiparkinsonian drugs for rescue medication (including soluble levodopa formulations).
• Concomitant treatment with apomorphine, MAO-A inhibitors or non-selective MAO inhibitors.
• Known hypersensitivity to active substances or to any of the excipients of the study drugs.
• Participation in other drug studies within 60 days prior to study entry
• Unsuitable veins for repeated venopuncture.
• Blood donation or loss of significant amount of blood within 60 days prior to the screening.