Clozapine is an atypical anti-psychotic medication that has proved useful in the management of both psychotic and mood disorders and that has been shown to decrease aggression and the risk of suicide, which suggests that clozapine may be useful in the management of severe borderline personality disorder. Here we present the case of a 36 year old female with severe borderline personality disorder with symptoms of psychosis, aggression and violence. We discuss how treatment with clozapine resulted in a marked clinical improvement in this patient.