An open, non-randomised, multinational, multicentre direct switch study in levodopa-treated Parkinson's disease patients suffering from early wearing-off in Parkinson's disease. The study will consist of 2 consecutive periods: screening period and study treatment period. Duration of the study will be up to 8 weeks for each subject. The study treatment dosage will be determined by the subject's current, separately administered standard levodopa/DDCI treatment (3-4 doses per day, maximum of total daily dose of 600 mg levodopa) which will be switched to an equivalent dose of Stalevo® without changing the number of doses per day. The levodopa daily dose during Stalevo® treatment may be adjusted according to the study subject's clinical response.

See 'Brief summary'.

Inclusion Criteria:

• Subjects with idiopathic Parkinson's disease and early wearing-off symptoms treated with standard levodopa/DDCI treatment
• Age >35 - years
• Hoehn and Yahr stage 1-3 performed during the 'ON'-stage
• At least 1 symptom identified by WOQ-9
• Dosing frequency of 3-4 doses of standard-release levodopa/DDCI (maximum total daily dose of 600 mg of levodopa)

Exclusion Criteria:

• Atypical or symptomatic Parkinson's disease
• Unpredictable OFF-periods
• Any peak-dose dyskinesia. 'OFF'-state dystonia is allowed
• Use of any rescue medications to treat symptoms of 'OFF'-state. 1 dose of soluble levodopa/DDCI is allowed.
• Concomitant treatment with non-selective monoamine oxidase (MAO) inhibitor or simultaneous use of higher than recommended doses of MAO-A and MAO-B inhibitors (selegiline 10 mg or rasagiline 1 mg allowed) or use of apomorphine.