Psychiatric diagnosis provides suitable tools for dealing with emergency situations, for the possible use of drugs and for building a therapeutic relationship. For this reason, it is important to keep the classification diagnosis, according to the categories of psychiatric nosography, in close relationship with the use of categories – theoretical and clinical – derived from psychoanalytic models. The article examines some conceptions of the role of psychoanalytic diagnostic criteria in psychiatry, offering in the second part a focus on the conception of adolescent development – with particular attention to the relationship between infantile super-ego and adult ego ideal – and on the criteria of activity and passivity of the ego as diagnostic tools for evaluating the strength of the adolescent's ego in the evolution of therapy.