The subject of biomaterials science concerns artificial materials used in medical devices to repair or reconstruct natural human tissue damaged by disease or trauma. It embraces the emerging field of tissue engineering, where artificial materials are used as scaffolds to provide the architecture for replacement organs. As such, the field raises numerous ethical issues, which are reviewed in this paper. These include the use of animal models, the testing materials and devices in patients, and what may be viewed as potential (...) abuses, where augmentation and repair are carried out for cosmetic as opposed to clinical reasons. The paper gives detailed consideration of the recent problems of metal-on-metal hip replacements as an exemplar of some of the key ethical issues that arise in this field. (shrink)