The Washington University Psychiatry Clinic, St Louis, study began with the systematic clinical evaluation of a cross section of 500 of the clinic's patients. This was followed by a "blind" follow-up of the index subjects and a blind study of first-degree relatives. This report deals with the diagnosis of schizophrenia at index, at follow-up, and among the first-degree relatives. The results indicate that the criteria used for the diagnosis of schizophrenia select patients who show a high degree of diagnostic consistency over many years, although not all patients who meet these criteria after follow-up receive the diagnosis of schizophrenia initially. Most important, the diagnostic criteria select cases associated with a strong familial increase in the risk of schizophrenia (nearly fivefold). The follow-up results indicate also that Feighner-positive schizophrenics often experience intercurrent depressions, but that the presence of such depressions does not affect the familial incidence of either schizophrenia or primary affective disorders.