It is generally believed that some abusive parents if untreated eventually kill their children and "the murder of a child is the final chapter in his history of maltreatment." Yet only few authors have investigated the homicide of abused children. In this paper the authors report on a study of 8 filicidal and 52 abusive mothers referred to them by courts for pre-trial psychiatric evaluation. They found that there were significant differences between the two groups in that all (100%) of the filicidal women suffered from a major psychiatric illness before and at the time of committing the murder of their child while only 4 (7.7%) abusive mothers had a major psychiatric illness (x2 = 24.41, df = 1, p less than .001). They conclude from this study that the filicidal mothers are different from abusive mothers and that the risk of fatality as a complication of child abuse increases significantly when the mental illness is present in the mother. They point to the implications of their findings for child protection and intervention procedures and suggest that one should act very vigorously and take the child into protective custody when the mother is found to have a major psychiatric illness.