On November 13, 1998, a workshop was held at the National Institute of Standards and Technology (NIST) to obtain a clearer assessment of the current needs for reference biomaterials (RBMs) with regard to standards, research, and regulatory purposes. In these applications, the RBMs would be used (as are other reference materials) for any of three main purposes: to help develop accurate methods of analysis (reference methods); to calibrate measurement systems; and to assure the long-term adequacy and integrity of measurement quality assurance programs. The workshop established needs and priorities that strongly reflect the current status of materials selection within three biomaterial areas-orthopedic applications, cardiovascular applications, and tissue-engineered medical products. The workshop was an outgrowth of an interagency agreement among NIST, The National Institute of Health (NIH), and the Food and Drug Administration (FDA) to cooperate in the development of reference materials. NIST, in cooperation with the NIH, the FDA, and others, is facilitating the development of needed RBMs.