The article presents a new view on manifestations of neurotic syndromes and their relations to defense mechanisms. The authors consider interrelations between four syndromes – Marilyn syndrome, impostor syndrome, learned helplessness, vernacular Stockholm syndrome) and 20 defense mechanisms, including dissociation, replacement, hypochondria, isolation, regression, passive aggression, etc. It was shown that each of the neurotic syndromes is closely linked to defense mechanisms, which allowed formulating practical recommendations for each subject to solve their problems. Thus, uniting the two phenomena into an interrelated structure forms a diagnostic tool, enabling to use a single feature to reveal a complex of diagnostic parameters, like characteristic personality features, behavior strategies, and anamnesis of child-parent relations; this serves as the basis for predicting the person’s behavior, the available and potential resources, and the possible ways of overcoming the current problem. Using such a tool allows significantly simplifying and expediting the diagnostic and therapeutic work of a practical psychologist.