In 1968, an ad hoc committee of Harvard faculty publicly redefined death as "brain death". What interests and issues compelled the redefinition of death, and formed the "spirit" of this precedent-setting policy? This paper reports on an historical study of the files of the Harvard ad hoc committee, the proceedings of an international conference on ethical issues in organ transplantation, and a review of the medical literature and media in the decades preceding the redefinition of death. This analysis of the technological and professional forces involved in the redefinition of death in 1968 questions two common theses: that technological "progress", primarily in the areas of life support and electroencephalography, literally created brain-dead bodies and dictated their defining features (respectively), and that Harvard's definition of brain death by committee constituted a net loss of autonomy for medicine. In fact, medical researchers through the 1960s disputed and negotiated many features of the brain death syndrome, and transplantation interests-perhaps more kidney than heart-played a particularly influential role in tailoring the final criteria put forth by Harvard in 1968. It is also doubtful whether Harvard's definition of brain death by multidisciplinary committee undermined medical privilege and autonomy. The Harvard Ad Hoc Committee may not have succeeded in establishing definitive, indisputable brain death criteria and ensuring their consistent application to all clinical cases of brain death. However, it did gain significant ground for transplant and other medical interests by (1) establishing brain death as a technical "fact" and the definition of brain death as an exercise for medical theorists, (2) involving non-medical ethics and humanities experts in supporting the technical redefinition of death, and, (3) successfully involving transplant surgeons in the redefinition of death and attempting (albeit unsuccessfully) not to exclude them from the actual diagnosis of death in individual cases.