The effectiveness of memantine on the symptoms of Parkinson's disease was investigated in 67 patients (39 males, 28 females) mostly between 55 and 75 years. The study was multi-center placebo-controlled with four treatment groups, i. e. patients with and without pre- and after-treatment with other anti-Parkinson medication receiving either placebo or memantine as sole or additional medication. The analysis of 61 evaluable cases showed a positive statistically significant influence on the single symptom tremor as well as on the neurological overall symptomatology (Webster-scale total score). Despite the inadequately ascertained mode of action memantine promises success particularly in milder and initial forms of the Parkinson syndrome either used as monotherapy or as an adjuvant.