A sample of 195 physicians and nurses likely to be involved in organ procurement for transplantation was interviewed about knowledge, personal concepts, and attitudes concerning “brain death” and organ donation. Only 68 respondents (35%) correctly identified the legal and medical criteria for determining death. Personal concepts of death varied widely. Most respondents (58%) did not use a coherent concept of death consistently; others (19%) had a concept of death that was logically consistent with changing the whole-brain standard to classify anencephalics and patients in a persistent vegetative state as dead. The findings demonstrate confusion about correct criteria for determining death and differences in concepts of death that might prove troublesome to the transplantation enterprise. We conclude that health professionals should do more to resolve the clinical and conceptual issues in the definition and determination of death before policies concerning organ retrieval are changed. © 1989, American Medical Association. All rights reserved.