In this article, the authors examine how the potential success of head/body transplantation raises questions as to how halakha—Jewish law and jurisprudence—might draw the line between determining whether a person is dead or alive. In presenting the primary Talmudic passages that refer to determination of life and death, and their discussion among halakhists and halakhic decisors, the authors show how the halakha might determine the demarcation between life and death as it applies to head/body transplants or potentially other innovations in medical technology.