In a study of White and Coloured schizophrenic patients, auditory hallucinations were reported to occur in one language only, the earliest the patients had learned. The patients' mental performance was relatively better when the non-home language was used. In the psychosis of toxic, drug, and organic origin and in epilepsy, hallucinations may be multilingual, in contrast to schizophrenia. This is of value in differential diagnosis. A case of paranoid psychosis in which a White man had extensive delusions with auditory hallucinations in his native language, but was non-psychotic and denied his delusions when conversing in another, is described. Hallucinations that alternated between English, Afrikaans and Xhosa in a case of non-schizophrenic hallucinosis is discussed. It is suggested that a defect of the system for verbal thought is implicated in the production of 'voices' in schizophrenia, involving the coding and processing of language.S. Afr. Med. J., 45, 1391 (1971)