Medical device manufacturers usually do not make the component materials that go into their devices, and yet they are responsible for demonstrating that the materials in the devices are safe. Product clinical performance design criteria aside, device manufacturers must carefully consider the component material's surface activity, potential extractable components, and their potential effect on the host. To address this issue, in May 1995, FDA issued a blue book memorandum announcing that the old Tripartite Guidance would be replaced with ISO 10993 as the criterion for evaluating the safety of materials used in medical devices. This white paper focuses on silicone, but the methodology is applicable to many other biomaterials including thermoplastics, thermosets, synthetic and natural rubbers, composites, and metallics.