Neuromelanin is closely linked to Parkinson's disease, but is it the cause of the illness? The main pathology of Parkinson's disease is a loss of pigmented brain-stem neurones, and neuromelanin or its precursors might be cytotoxic. However, the cellular marker of Parkinsonian pathology, the Lewy body, is not confined to neurones containing neuromelanin. There are areas of the brain, of which the substantia innominata is a good example, which contain no neuromelanin or catecholaminergic neurones, but whose cells are packed with Lewy bodies and die. It is concluded that it is not neuromelanin, but the Lewy body which holds the key to Parkinson's disease.