Twenty-two patients with a diagnosis of schizophrenia according to DSM-III-R and ICD-10 criteria, for whom the long-term courses of illness were all well documented, were classified by 4 independent investigators using Leonhard's classification of endogenous psychoses. With regard to the large nosological groups of cycloid psychoses (including the subtypes of anxiety-happiness psychosis, confusional psychosis and motility psychosis), of unsystematic schizophrenias (including the subtypes of affect-laden paraphrenia, cataphasia and periodic catatonia), and of systematic schizophrenias (divided into systematic catatonias, systematic paraphrenias, and hebephrenias), is was possible to reach a high level of agreement in the diagnosis, representing a Cohen kappa coefficient of 0.82 and 0.89, respectively. In only 2 out of 22 patients were discrepancies observed in the assignment to the above-mentioned groups. This clearly shows the high reliability of Leonhard's classification, which allows a differentiated diagnostic and prognostic judgement of schizophrenic psychoses according to the DSM-III-R and ICD-10.