Some myths and traditional tales are reviewed in which filicidal mothers play a protagonist role. In her displaced form, the witch is ubiquitous in folklore. This imago is universal in fantasies and pavor nocturnus in children, regardless of the quality care of the maternal figures. To this phenomenon -the result of defensive externalization of primitive fears- a fundamental dimension is added when there exist a seeming corroboration of this dread by manifest murderous wishes and behaviour of the mother. Clinical examples are provided of this highly pathogenic circumstance, with special emphasis on the development of dissociation vs. repression, the evolution of symptoms in adulthood, and the interpretive and technical dilemmas posed by these cases.