This paper reviews the literature on the replacement child syndrome and examines its historical, theoretical, and biographical ramifications. Although a replacement child in a literal sense is one conceived to take the place of a deceased sibling, the concept may be extended to many other situations in which a child is put in the place of someone else in the family system. In his experience of survivor guilt for his deceased brother Julius, Freud may be regarded as such a metaphorical replacement child. The collective tragedy of the Holocaust gives the replacement child concept a special meaning, since the children born in its aftermath had to fill the void in the lives not only of individual parents but of the Jewish people as a whole. One of the coauthors of this paper, Leon Anisfeld, was born after World War II to parents who had lost previous spouses and children, and his personal experience as a replacement child informs the theoretical issues considered here.