The aim of this article is to outline the usefulness of deficit and defect categories in the process of psychotherapy in psychodynamic terms. Because there is no common definition of these concepts, at first the author analyses how they are used in a clinical practice (we talk about e.g. cognitive or different, emotional deficits organic or post psychotic defects). Sometimes these phrases have very pessimistic connotation for the outcome of psychotherapy. The author refers to different psychoanalytic theories (e.g. H. Kohut, M. Balint, H. Deutsch, F. Pine) to show that these concepts have their origin in two sources. The first one is the accumulation of psychological and neuropsychological knowledge on the determinants of irreversible changes in patient's personality. These changes result from brain dysfunctions, early relationships or developmental environment. The second source is the strong experience of countertransference inefficacy as well as limitations of psychotherapy as the method of facilitating positive changes in the patient's life. Clinical examples are used to show therapeutic implications of the discussed concepts. The author focuses on the necessity of distinction between deficit and dissociation, interpersonal nature of deficit and defect diagnosis as well as the possible determinants and consequences of premature diagnosis of deficit or defect.