The phenomenon of folie à deux has been a topical issue in psychiatry for more than a century. Mainly, genetic and psychodynamic factors are discussed controversially in terms of their relevance to the etiology of folie à deux. In this paper, effort is taken to reconceive the topic applying the criteria of a differentiated psychopathological classification. Based on the literature and on two own cases, we try to elaborate characteristical psychopathological features of folie à deux patients. We hypothesize that at least a substantial fraction could be classified as "folie simultanée" when Leonhard's criteria of the affect-laden paraphrenia are considered.