This paper deals with incest from the theoretical and clinical psychoanalytical viewpoint, without overlooking the various biological and socio-anthropological theories. Incestuous acting is differentiated from general sexual abuse and from incestuous phantasies. As well as the phenomenic aspects, the author analyses the conscious and unconscious levels that lead individuals to practice incest, as well as the damage that incest inflicts on developmental processes. The traumatic effect impairs psychic organization by dis-articulating the oedipal developmental stages and related drive vicissitudes as well as the real roles of the family members. The theme of the incest is discussed regarding the two crucial post-freudian psychoanalytical achievements: the exploration of early developmental aspects of the psyche (pre-oedipal stage) and the knowledge about the feminine and about women. This leads to the discussion of different psychoanalitical paradigms. The author further remarks the devastating effects, both at the intrapsychic and at the interpersonal dimension, of the failure to differentiate aspects of sensorial tenderness from the erotic. Within a context of generalized tendency of regressive defences towards indifferentiation in the present time, in wich the oedipal crux seems slackened if not avoided altogether, the author wonders whether perhaps incest provokes today less anxiety, less guilt and less horror, but no less damage.