74 patients with paranoiac psychoses were followed up. Paranoiac psychoses are characterized by affect-laden delusions, resemble the paranoias of Kraepelin, but have a better prognosis. 18 cases appeared to show a chronic course of illness, but only 1 case needed prolonged hospitalization in a mental hospital. Paranoiac psychoses are considered benign insofar as they have a nonschizophrenic long-term outcome. They resemble schizophrenic psychoses because the familial loading of psychoses is predominantly schizophrenic. To a great extent, the clinical picture revealed typical schizophrenic symptoms at the onset of the illness, so that at discharge from hospital there were often doubts as to whether psychoses should be classified as schizophrenias.