The purpose of this article is to describe some ethical considerations that have arisen during the design and implementation of the health examination surveys conducted by the National Center for Health Statistics of the Centers for Disease Control and Prevention. Three major areas of concern are discussed: sharing information from the study, banking and using banked tissue samples, and obligations for future testing of subjects. Specific concerns of sharing information include: when to inform, whom to inform, maintaining confidentiality, and how to inform individuals. Specific concerns of determining when sera will be banked and using banked samples include: depletion of samples for quality control, obtaining informed consent for unanticipated uses, access by others, and requests for batches of samples. Finally, specific concerns regarding future testing of subjects include: retesting for verification, retesting for interpretation, testing for different risk factors, and follow-up. Although existing surveys can provide experience or even suggest guidelines, the uniqueness of any new survey will generate unique ethical problems, requiring the careful formulation of unique solutions.