A systematic psychiatric follow-up study of 502 schizophrenics was carried out using the same well-defined criteria to evaluate the patients throughout the investigation. After an average course of disease of 22.4 years, 22.1% of the patients showed complete psychopathological remission, 43.2% had non-characteristic types of remission and 34.7% suffered from characteristic schizophrenic deficiency syndromes. At the time of the last follow-up investigation, 86.7% of the patients were living at home, while 13.3% were permanently hospitalized. Of the entire sample, 55.9% were found to be "socially recovered". Higher education, psychoreactive provocation, depressive traits, perception of delusions, catatonic agitation, non-characteristic thought disorders and symptoms of depersonalization at the onset of the illness tended to carry with them a favorable prognosis. On the other hand, low intelligence, abnormal primary personality, premorbid disturbances in social behavior, broken homes, prolonged prodromal stages, pneumoence-phalographically measurable atrophic or dysplastic changes in the brain ventricles as well as somatic and auditory hallucinations and predominance of hebephrenic symptoms at the onset of the illness tended to lead to an unfavorable prognosis. The principle of the basic reversibility of typical schizophrenic symptoms and the extensive irreversibility of the non-characteristic defect is important for the psychopathological and social long-term prognosis.