The delusional misidentification syndromes (DMSs) are psychopathologic phenomena in which a patient misidentifies persons, places, objects or events. The most common form of misidentification is the Capgras Syndrome (Capgras and Reboul-Lachaux, 1923), other types are Frégoli Syndrome (Courbon and Fail, 1927), Intermetamorphosis Syndrome (Courbon and Tusques, 1932) and Syndrome of Subjective Doubles (Christodoulou, 1978).

There are other syndromes, generally not included in DMSs, which share some common characteristics, like Mirrored Self, Reduplicative Paramnesia, Delusional Companions and Clonal Pluralization of the Self.

These delusions can be the greater part of the presentation or secondary to several psychiatric and neurological disorders.

The authors intend to describe the DMSs, including its definition, epidemiology, etiology, presentation and some considerations about treatment, prognosis and forensic psychiatry. Some of the hypotheses that have been suggested to explain these syndromes will be also addressed.

The authors conducted a literature review about delusional misidentification syndromes.

It’s important to physicians to be able to recognize these syndromes and be aware of the need to investigate the existence of possible organic diseases.

The patients with more structured delusions, as seen in DMSs, are more frequently involved in acts of violence. It’s imperative to assess the risk of aggression, mainly, against the ’impostor”, in order to prevent violent behavior.

There have been few systematic studies in broad samples about this theme. More research is needed.