Background: Even though the origin of the concept of shared delusion is not consensual, the term folie a deux was introduced in 1877 by two french researchers - Lasegue and Falret. According to the original concept, a person (inductor), cognitively dominant, develops a delusional idea that progressively imposes to a second person (induced), with whom he keeps a close relationship. The four psychopathologic subtypes known - folie imposee, folie simultanee, folie communiquee and folie induite, were described in the final of the XIX century, but its classification and con-ceptualization was assigned to the american researcher Gralnick (1942). Aim, materials and methods: It is intended to highlight some clinical aspects of the shared delusion disorder, its epidemiological and psycopathogenic characterization and therapeutical approach. In order to achieve it, the authors presented a clinical case report and respective non systematic literature review. Results: It is a case of shared delusion of the type folie imposee in a pair mother/son. The inductor (son) suffers from bipolar disorder and asperger syndrome and shared with his mother (induced and carer) a persecutory delusion. Conclusions: It is highlighted the importance of a social isolation context and close contact between both members in the genesis of the disease; it is discussed the subject of the cognitive dominance between the inductor and the induced and the implications of the separation of the pair mother/son, as primary therapeutic action.