Progressive ataxia frequently starts in adults without a familial background. These patients may suffer from an acquired ataxia or a genetically determined ataxia despite negative family history. In the majority of them, however, a genetic or acquired cause of ataxia cannot be identified suggesting a sporadic degenerative ataxia. They can be subdivided into two groups. In one group, the underlying brain disease is multiple system atrophy (MSA), specifically MSA of cerebellar type (MSA-C). The characteristic clinical feature of MSA is the presence of severe autonomic failure defined by orthostatic hypotension or urinary incontinence. The second group is distinguished from MSA-C by the lasting absence of severe autonomic failure. These patients have been designated as sporadic adult onset ataxia of unknown aetiology (SAOA). In the first years after ataxia onset, a distinction between MSA-C and SAOA is often not possible.