Multiple system atrophy (MSA) is a neurodegenerative disease of unclear etiology and pathogenesis. Clinically, there are combinations of extrapyramidal, cerebellar, pyramidal and autonomic dysfunctions. Diagnosis is sorted into different categories according to criteria. The appearance of hallucinations unrelated to medication is considered to be a criterion of exclusion for the diagnosis of MSA. A case is described in which delusional parasitosis occurred as a possible initial syndrome of MSA. The simultaneous appearance of MSA and a psychotic disease is possible and has been described repeatedly. Therefore, this criterion of exclusion is discussed. Delusional parasitosis is an unspecific syndrome of multifactorial genesis. Partial remission of the monothematic symptomatology of delusion shows that a continuous and consequent therapy with neuroleptics seems to be promising. In the case presented, the good efficacy of olanzapine in low dosage over an extended period of time is described.