The National Institutes of Health and other federal health agencies are considering establishing a national biobank to study the roles of genes and environment in health. We assessed the public's attitudes toward the proposed biobank, including preferences for providing informed consent. Sixteen focus groups were conducted, and themes arising from the focus groups were tested in a large, representative survey (n=4659) of the general population. Our research demonstrates that when considering participating in a genomic biobank, individuals want ongoing choices and control over access to their samples and information.