This paper describes a series of 13 cases of parents who have killed their children. A review of the literature suggests that child murder is infrequent and committed in most instances by the parents. Most attention has been directed to the universal phenomenon of child abuse. The killing of a child in our culture is viewed much more seriously than the killing of a newborn infant, legally defined as infanticide. Only a few authors have reported on the former, and their studies tend to demonstrate that a higher proportion of these crimes are perpetrated by mothers. Homicidal behaviour in parents may also be associated with common forms of psychiatric disorders and may manifest as the extended suicide phenomenon (homicide reported with major depressive illness). Attributes of both parents and the children are also significant factors to be considered. In a retrospective study the relevant demographic and clinical data of a series of 13 cases are reviewed. The diagnostic classification using DSM-III-R is discussed in detail. A higher incidence of maternal perpetrators was found and is consistent with previous studies. Exposure to a variety of psychosocial stresses appears to have been a major factor. Similarly the suicidal history and behaviour of the subjects is significant. Affective disorder appears to be an important diagnostic category. Finally, the role of psychiatric and other social agencies is considered in relation to the murder of children. A better understanding of this phenomenon is indicated in order to help us deal with families at risk.