The Special Issue of Nanomaterials "Frontiers in Nanotoxicology" highlights the modern problems of nanotoxicology and nanobiomedicine, including the toxicity of metal-based, silicon-based, carbon-based, and other types of nanoparticles, occupational safety of nanoproduction workers, comprehensive assessment on new biomedical nanomaterials, improvement of nanotoxicology methods, as well as the current state and prospects of research in the fields of theoretical, experimental, and toxicological aspects of the prospective biomedical application of functionalized magnetic nanoparticles activated by a low-frequency non-heating alternating magnetic field, biomedical applications and the toxicity of graphene nanoribbons, and fetotoxicity of nanoparticles [...].