This is an open-label, prospective post marketing surveillance study to be performed in Sweden. Only data of patients idiopathic PD should be documented, in whom the treating physician plans to initiate a pharmacotherapy with PPX ER independent of this observational study. The questionnaires (Morisky Medication Adherence Measure, patient preference scale, CGI-I, PGI-I) will be used to document routine care in a standardized way and thus ensure high validity of the observational data. As the degree medication adherence of patients is routinely evaluated by their physicians, as is patient preference and possible symptom improvement after initiation of a new therapy, the patient questionnaires will be used to standardise medical routine care and to ensure validity of observational data.