The clinical course of an instance of periodic psychosis in puberty is described. The findings in this and similar patients discussed in the literature indicate the existence of a psychotic syndrome in boys and girls that begins at puberty. The partial similarity to another periodic cyclic syndrome, that which occurs postpartum, is pointed out. The findings in cases such as the one reported show the inadequacy of hypotheses concerning the sociologic etiology of so-called schizophrenia and also indicate that the diagnosis of schizophrenia does not apply to a homogeneous group of patients.Abstract Teaser