In a 15-year follow-up study, we used a comparative approach to assess course and outcome for all functional psychoses. The presented results focus on negative symptoms and refer to a sample of 76 patients with schizophrenia, 38 patients with a schizoaffective disorder and 32 patients with an affective disorder according to ICD-9. These patients were assessed at their first psychiatric hospitalization and 15 years later. In summary, the findings indicate that the course and outcome of schizophrenia is less favorable than that of affective and schizoaffective disorders. Negative symptoms occurred in all functional psychoses, but were more frequent and prominent in the schizophrenic group than in the other two diagnostic groups at any time of assessment. Narrower concepts of negative symptoms, conceptualized as the deficit syndrome, seem to be specific for schizophrenia and appear quite rarely in patients with affective psychoses. Overall, our study supports Kraepelin's original hypothesis that bifurcated the psychoses into the affective psychoses and schizophrenia, whereby the latter have a more deleterious long-term course and outcome.