Mental puerility is a syndrome found by Dupre at the beginning of the Twentieth century. This syndrome was first observed in hysteria, senile dementia, encephalon organic complaints, poisoning. It was understood like regression to mentality childhood: childlike attitudes, postures, acts and language. After Dupre, some French authors (H. Claude, E. Minkowski, etc.) noted puerility in psychosis (schizomania, schizophrenia). Regression, reappearance, stopped development? The interpretations according to the authors vary. We'll see that another interpretation can be proposed: puerility in psychosis can be explained like delusion compensation, without hallucinations, without delusion or delirium, like a defense process against unbearable reality. This "state" of childhood could be a solution, a psychic answer in order to avoid disruption, mental disorganization, delirious state. This new interpretation will find theoretical supports with failing narcissism, failure of "mirror stage", massive identification with childhood, etc. These psychotic persons with pathological puerility lead us to think that they could have a "delirious puerility of compensation". (C) 2014 Elsevier Masson SAS. All rights reserved.