Alpha-synuclein is a natively unfolded protein associated with a number of neurodegenerative disorders that include Parkinson's disease. In the past, research has focused on the fibrillar form of the protein. Current research now indicates that oligomeric alpha-synuclein is the form of the protein most likely to causes neuronal death. Recent research has suggested that a unique oligomer associated with the copper binding capacity of the protein is the neurotoxic form of the protein. This review looks at the evidence for this possibility.