Their inherent lack of dislocations and hence slip planes leads to exceptionally high strength and elasticity, approaching the theoretical limit. While oxide glasses and ceramics exhibit low toughness and brittle failure, BMGs can display toughness comparable to crystalline metals. [ 2 ] The lack of grain structure means that BMGs are homogeneous and exhibit isotropic behavior, even at sub-micrometer length scales, and, without grain boundaries or precipitates as oxidation sites, corrosion rates are significantly reduced compared to conventional metals.BMGs soften above an alloy-specifi c glass-transition temperature ( T g ) before eventual, time-dependent, crystallization at a higher, crystallization temperature ( T x ). In this supercooled liquid region (SCLR) between T g and T x , the viscous BMGs may be plastically shaped under low applied forces using polymer-processing techniques, such as hot embossing, extrusion, foaming, and injection and blow moulding, before again cooling to a solid metallic glass. With relatively low processing temperatures and no solidifi cation shrinkage, parts can be formed to netshape with excellent accuracy, and geometries, and surface patterns previously diffi cult in metals can be achieved with ease. [3][4][5][6][7] Such remarkable properties and behavior have led to significant interest in BMGs as engineering materials over the past 20 years, but it is only recently that their potential for use as a biomaterial has been studied. [ 8 ] To date, our understanding of material biocompatiblity has evolved mainly through empirical testing, observing the interaction of materials with cells and host tissue in vitro and in vivo. Materials can induce host responses varying from local and systemic infl ammation, hypersensistivity, toxicity, and even tumorogenesis, meaning that thorough evidence of material safety is required before regulatory approval and clinical translation. We now largely recognise the material characteristics that generate both favorable and undesired host responses, as outlined by Williams, [ 9 ] offering the opportunity for informed material design, while being cognisant that biocompatibility is specifi c to the application and host environment. [ 10 ] The original requirement of fi rst generation "biocompatible" materials was bio-inertness. [ 11 ] This included a resistance to corrosion in the body, and here Ti-and Co-based alloys scored highly. [ 12 ] Less-inert metals, such as Mg, were therefore not deemed suitable, although the ions released on dissolution are generally not harmful to the human body. However, current design requirements for biomaterials, including most recently biometals, include eliciting an appropriate host response, [ 13 ] and this can include the need to biodegrade and resorb. There are potential advantages for BMGs that span applications of With increasing knowledge of the materials science of bulk metallic glasses (BMGs) and improvements in their properties and processing, they have started to become candidate materials for biomedical dev...