A case of deliberate genital self-mutilation in a woman with familial schizophrenia is presented. Such behaviour, though well recognized in females with severe personality disorders, is extremely rare in female psychotics. The genital mutilation may be partially understood as a consequence of delusionally motivated action against a background of low self-esteem, premorbid body-image preoccupation, forced early sexual activity and hence profound ambivalence towards adult sexuality. Dealing with this constructively was hampered by a cognitive style characterized by impaired reasoning and reality testing. Tests of reasoning, judgement and reality testing showed deficits, and computed tomography revealed dilatation of the left frontal ventricular system. Both neuropsychological and psychodynamic factors appeared to be of relevance in this case.