The author explores the psychodynamics of maternal filicide from an object relations perspective. Among psychotic women, the murder of the child reflects a critical interplay among the mother's neurobiology, constitution, developmental experiences, and complex internal object world. Two types of personality structure are discussed. For the disorganized type, the psychodynamic scenario involves attempts to contend with the danger of massive internal breakdown. For the organized type, the scenario involves attempts to contend with the danger of persecution and annihilation. For these women, physical violence is used because of failures in mentalization, and is an enactment of catastrophic internal anxieties.