The first reference to the shared delusions emerged in France in the nineteenth century. Shared delusions can be classified in three frames with different nosological value: simultaneous folie à deux, imposed folie à deux and communicated folie à deux.

A review of the structures of presentation of this psychiatric disorder through a case report and checking the categorization of the classic folie à deux in the current diagnostic manuals.

Discussion through a case report of delusional disorder among twins. After several interviews with the patients we found that both have a complex delusional system, structured and bizarre at the same time. There was a clearly paranoid tinge in the narration which main theme is religion.

Delusional clinical appears identically and simultaneously in both subjects with equal readiness and doesn’t give up after the admission of the patients in two different psychiatric hospitalization units.

In the ICD-10 and DSM-5, diagnostics would be different depending on the kind of folie à deux. In simultaneous folie à deux and communicated folie à deux the dominant partner would receive a diagnosis of delusional disorder with ICD-10 and DSM-5. The acceptor partner would receive a diagnosis of delusional disorder induced with the ICD-10 and a diagnosis of unspecified schizophrenia spectrum and other psychotic disorder with the DSM-5. In a simultaneous folie à deux, both subjects would have a diagnosis of delusional disorder in both manuals. We think that this is the right choice.

The authors have not supplied their declaration of competing interest.