This review aims to collate some of the extensive literature on the schizophrenia-like psychoses occurring in association with organic cerebral disorders. Their relationship to "true' schizophrenia is considered clinically, genetically and conceptually. The conclusions reached are as follows: The association of many organic cerebral disorders with schizophrenia exceeds chance expectation. Although there may be group differences, these psychoses include a range of symptoms similar to those found in the general run of psychoses diagnosed as schizophrenia. These psychoses usually occur in patients without genetic loading for schizophrenia. Organic cerebral disorder occurs in a substantial minority of patients diagnosed as schizophrenic and is of particular importance in the psychoses of childhood and old age. The site of the brain lesion is more important than the predisposition of the patient in the genesis of these psychoses, and lesions in the temporal lobe and diencephalon are of particular significance.