This paper reflects on the clinical phenomena of mental and physical self-attack as encountered in everyday psychotherapeutic practice in the NHS. The author considers two distinct but closely related internal dynamics which he terms ‘melancholic’ and ‘antilibidinal’. In both, there is a sadomasochistic structure which serves a number of defensive purposes for the individual. The origins and functioning of these structures are explored in the clinical material. These defensive systems are often perversely rewarding for the patient and highly resistant to change. The author discusses some of the major obstacles to working therapeutically in this area, and emphasizes the role of the transference and countertransference in helping the therapist to understand who is doing what to whom within the therapeutic relationship and within the patient. Although the paper deals with theoretical issues the emphasis throughout is on clinical understanding and effectiveness within a (mainly) once-weekly analytic setting.