The factors to which the pathogenesis of paranoia is ascribed are predisposition, personality and environment. This paper deals with further etiological preconditions such as psychoorganic impairment, convulsive disorders and physical handicaps together with their psychoreactive processing, based on detailed case reports. Such patients are relatively frequent within the (epidemiologically small) group comprising paranoia. The psychodynamic factors underlying the sensitive processing of physical handicaps are described, with means of prevention being discussed in conclusion.