The primary objective of this study is to determine that pramipexole (Sifrol) 0.25 mg to 0.75 mg daily is not inferior to levodopa 100 mg to 300 mg (in combination with benserazide 25mg to 75mg = Madopar DR) daily in the treatment of patients with idiopathic restless legs syndrome fulfilling the International Diagnostic Criteria. The efficacy parameters include an objective measure of the leg movements during the time spent in bed, and a quantitative clinical assessment of the severity of RLS, in the form of the RLS-score. In addition, the efficacy evaluations aim at comparing the impact of pramipexole and levodopa on outcome measures such as quality of life and sleep.