Abstract: The present invention relates to the field of medicine and in particular to Parkinson's disease (PD). Specifically the present invention relates to methods and means for early detection of PD. The invention relates also to methods and means for treatment or prophylaxis of PD. In the method of the invention a probability of a subject developing or having Parkinson's disease (PD) is determined by measuring the relative abundances of one or multiple microbial tax a in a sample from a subject; and the probability of the subject developing or having PD is determined based on the measured abundances. The present invention provides a novel approach for the diagnostics of PD.