Parkinson disease (PD) is one of the neurodegenerative diseases. The prevalence of PD is increasing due to the general increase of the population over 65 years. An estimate shows that there are about 6.000 – 8.000 people suffering from PD in Denmark. The pathology behind PD is loss of dopaminerge cells in substantia nigra. PD is primarily diagnosed clinically by tremor, bradykinesia, rigidity and postural instability. However, several agents have been suggested as possible biomarkers. One of these is α-synuclein. Aim The aim of this study is to determine if the concentration of α-synuclein and α- synuclein oligomer the in the cerebrospinal fluid can be used as a biomarker for diagnosing PD. Design A total of 36 patients diagnosed with PD and 36 controls matched in sex and age were included in this study. The PD patients were classified according to the Hoehn-Yahr classification. The concentration of α-synuclein and the α-synuclein oligomer were determined with the use of ELISA technique. Results At this time, we are making preparations for the biochemical analysis. We hope that this study can help determine if α-synuclein and the oligomer can be used as a reliable biomarker for PD.