The primary objective is to assess sustained efficacy in patients who have responded to a 6 month treatment with open-label pramipexole.

Secondary objectives are the measurement of severity of the RLS, assessment of early withdrawal phenomena after termination of trial medication, augmentation under treatment, sleepiness, quality of life and subjective wellbeing, the physician's clinical assessment of symptom severity and improvement. Another secondary objective is safety and tolerability of treatment.

Inclusion Criteria:

• Male or female out-patients aged 18-80
• Diagnosis of idiopathic RLS according to the Clinical RLS criteria of the International RLS Study Group
• RLSRS score > 15
• RLS symptoms present at least 2 to 3 days per week within the last 3 months
• Written informed consent

Exclusion Criteria:

• Women of childbearing potential without adequate contraception, or breastfeeding
• Concomitant or previous pharmacologically therapy of RLS
• Clinically significant renal disease, and/or hepatic disease
• Any of the following lab results at screening: Hb, TSH, T3 or T4, clinically significantly out of normal range, positive urine drug screen
• Other clinically significant metabolic-endocrine (including diabetes mellitus requiring insulin therapy), haematological, gastro-intestinal disease or pulmonary disease . Poorly controlled cardiovascular disease
• History or clinical signs of peripheral neuropathy (PNP), myelopathy or multiple sclerosis or any other neurological disease, with potential to secondarily cause RLS symptoms, history of or clinical signs for any form of epilepsy or seizures
• Presence of any sleep disorder
• History of schizophrenia or any psychotic disorder, history of mental disorders, alcohol abuse or drug addiction
• History of or clinical signs of malign neoplasm
• Patients on a shift-work-schedule, or who are otherwise unable to follow a regular sleep-wake cycle enabling use of study medication at times indicated
• Allergic to pramipexole or its excipients