A Pilot Study to Assess Efficacy and Safety of Pardoprunox as Adjunct Therapy to L-dopa in the Treatment of Patients With Parkinson's Disease Experiencing Motor Fluctuations and Dyskinesia.

Inclusion Criteria * Patients who have signed informed consent * Diagnosis of idiopathic Parkinson's Disease * Stable treatment with L-dopa and dopamine agonist for at least 28 days prior to randomization * Presence of a recognizable ON and OFF state (motor fluctuations) * Minimum hours of OFF-time per day of 1.5 hours (during waking hours including early morning akinesia) as recorded per baseline diaries * Minimum hours of ON time with troublesome dyskinesia of 2 hours (during waking hours) as recorded per baseline diaries * Prevalent expression of severely disabling dyskinesias during the waking day, i.e. dyskinesias are present at least 25% of the waking hours (UPDRS Part 4 item 32 \>= 2) in combination with a degree of disability which is moderate or higher (UPDRS Part 4 item 33 \>=2) Exclusion Criteria * Diagnosis is unclear or a suspicion of other parkinsonian syndromes * Patients who have undergone surgery for the treatment of PD