The concept of acute delirious puff refers to a transient psychotic state characterized by the sudden outbreak of a polymorphic delusional state in its themes and mecha- nisms. Magnan, in the late of nineteenth century, insti- gated the initial description of this concept. Rediscovered by Henri EY, it's current presence in the French psychiatry despite various attempts to dismantle it results from a singularity based on five cardinal points: it affects young adults, its onset is sudden, delusions are polymorphic and not systematic, there is a marked emotional lability and access is rapidly cured. This entity reveals vulnerability and must be understood carefully by the general practitioner, the issue being the prevention of progression to chronic psychosis.