This paper is based on a follow-up of 36 cases, extending over several years. Obsessive psychosis is defined here as an illness of long duration characterized by remissions, which may be either spontaneous or induced by treatment, when the patients are free from their symptoms. The remissions may extend over months and even over years; however, in the majority of cases a relapse may be expected. The ability to form obsessive symptoms appears to be the factor counteracting the disintegration of personality. As to differentiating this illness from schizophrenia, the emotional life of patients suffering from obsessive psychosis is not shallow and there is no intellectual impairment even in cases of long standing. Unlike schizophrenics, patients with obsessive psychosis do not suffer from hallucinations or loosening of associations.