This paper is focused on the clinical effectiveness of long-term psychoanalytic psychotherapy in the treatment of severe forms of depression. Empirical data, recent reviews, and exemplary research data prove that this form of therapy represents an effective method of treating depression, especially its more severe forms. The author also presents a brief discussion of some crucial theoretical notes regarding psychoanalytic understanding of severe and chronic forms of depressive disorders: the classic psychoanalytic view of depression as difficulty in coping with loss, which leads to turning aggression to the inside; the differentiation between normal, neurotic, and psychotic depression; and the idea of psychotic functioning as an aspect of mind which is withdrawn from reality. The main part of this article is a clinical case of psychotherapy conducted in line with technical clues derived from theoretical premises: transference was used to co-create representations of experiences which had remained unsusceptible to psychological processing.