In this article a recent development is explained within psychoanalytic tradition, the structural diagnostics. Structural psychodiagnostics are the first step in the psychodiagnostic activity directed at diagnosing the ego and in this way personality structure. Otto Kernberg proposed to use three categories: the neurotic personality organization, the borderline personality organization and the psychotic personality organization. Three overriding structural characteristics dominate and differentiate the personality organizations: identity integration versus identity diffusion, a constellation of advanced or primitive defensive operations, presence or absence of reality testing. The structural interview is also described in this article which is used for this diagnosis. Especially important in this interview are: clarification, confrontation and interpretation in the here and now of identity conflicts, defensive operations and reality distortions. A critical analysis of the structural diagnostics completes this article.