OBJECTIVES: To prospectively evaluate the health-related quality of life of patients with Parkinson’s disease (PD) in Germany over a 12 month observation period. METHODS: The study included 145 patients with PD (mean age: 67.3±9.6 years) in Germany. Patients were asked to complete the EQ-5D, Parkinson’s Disease Quality of life questionnaire (PDQL) and the Parkinson’s Disease questionnaire-39 (PDQ-39). In addition, the occurrence of depression and dementia were investigated using the Beck’s Depression Inventory (BDI) and the Mini-Mental-State-Examination (MMSE). Evaluations were performed at baseline, 3, 6 and 12 months. Disease severity was documented by the Unified Parkinson’s Disease Rating Scale (UPDRS) and the Hoehn & Yahr (HY) scale. RESULTS: At baseline mean VAS-value was 59.9±18.0 and mean EQ-5D index was 0.74±0.25. HRQoL of patients suffering from dyskinesias (47.5) were lower than in patients without dyskinesias (61.7). In HY-stage I mean VAS was 72.8±16.9 vs. HY V 45.7±10.6. At 12 months the overall PDQ-39 score declined slightly from baseline 29.4±17.4 (n= 137) to 25.6±16.2 (n= 128). Similar results were found for the PDQL overall score (118.6±27.5 (n=87) compared to 122.8±26.1 (n= 72)) and the EQ-5D index (0.74±0.25 (n=115) compared to 0.74±0.25 (n=115). No significant changes were found for the clinical scores (UPDRS and Hoehn & Yahr scale) and the psychometric questionnaires (MMSE and BDI). CONCLUSIONS: The PDQ-39, PDQL and the EQ-5D are instruments delivering stable test results for PD patients. There is no significant change during the 12-months abservation period in all used instruments. As this study will have a follow-up up to three years a more detailed analysis of time-dependent changes of HRQoL will be possible. Depression and motor complications are the factors with the highest impact on health-related quality of life in PD patients.