The spectrum of Lewy body disorders includes not only Parkinson's disease, dementia with Lewy bodies and Parkinson's disease associated dementia but also Lewy body dysphagia and autonomic failure with Lewy bodies. In the last years an increasing number of cases showing Lewy body pathology has been recognised at autopsy. In fact, dementia with Lewy bodies is thought to be the second most frequent degenerative cause of cognitive decline in elderly after Alzheimer's disease, representing about 20% of dementia cases. The clinical diagnosis of dementia with Lewy bodies and of Parkinson's disease dementia is determinant for prognosis and therapeutic management, namely for avoiding increased sensibility to neuroleptics. The recent progress of neuropathology in this field made it possible to define clinical and neuropathological guidelines for the diagnosis. This review briefly describes the most important data of all Lewy body related disorders.