Intravenous application of amantadine sulphate induces a rapid improvement of motor symptoms in Parkinson's disease (PD), but there are no trials on the efficacy of this compound on bradykinesia, rigidity and tremor in detail in combination with standardized instrumental measurement of tapping and peg insertion abilities. We treated 31 stable non fluctuating PD patients with amantadine, scored motor symptoms of both arms and performed peg insertion and tapping under cued conditions before and after 3 days. Motor symptoms and peg insertion significantly improved in contrast to tapping. Tapping asks for repetitive performance of simple standardized movements, therefore it needs low cognitive efforts. Since peg insertion depends on more complex movements and thus more dopamine dependent cognitive processes, it improved after application of the indirect dopaminomimetic substance amantadine.