Parkinson's disease is a common neurodegenerative disorder of unknown aetiology. A pathogenic point mutation within the a-synuclein gene has recently been identified in one Italian-American kindred and three families of Greek origin with parkinsonism. DNA from 70 patients with Parkinson's disease was screened for this G209A mutation. No samples were positive for the mutation, suggesting that it is not relevant for most patients with sporadic idiopathic Parkinson's disease.