Objective To study the clinical,pathological characteristics and diagnosis of multiple system atrophy(MSA).Methods Among 4 cases of MSA,2 of them were from clinical data,the other 2were frum pathological data.Two cases verified by autopsy were investigated using Hematoxylin-eosi,Kltiver.Barrera and Gallvas-Braak silver staining and confirmed by immunohistochemistry using ubiquitin,α-synuclein staining.Results All 4 patients were male.aged 51-76.Case No.1 wag diagnosed as Parkinson's svndrome.Case No.2 was diagnosed as spinal ataxia cerebella,and the other two eases were diagnosed as MSA.The following changes were found by pathological studies.Macroscopic atrophies were presented in pens and cerebella.as well as putamen,globus pallidus and substantia nigra.Cerebral ventricles were dilated.Neuronal lOSS and gliosis could be seen at cerebral cortex.nigrostriatal.globus pallidus,pontine nuclei,subslantia innominata,inferior olives,doral motor nucleus of vagus,cerebellum antl intermediolateral column of the spinal cord.In the white matter of these regions cytoplasmic inclusions bodies were extensively present in oligodendrocytes.Conclusions Olivopontocerebellar atrophy mainly shows the,clinical symptoms of pens,cerebellum,and autonomic nerves damage;Shy-Drager syndrome presents mainly with the erecting hypotenstion symptom,while striatonigral degeneration mainly involves extrapyramidal system.As these three diseases share the common basic pathological changes,they are preferred to be classified as the subtype of MSA.