While exposure to nanoparticles is a growing concern, research into their toxicological impact and possible hazard for human health is limited. There remains a lack of information concerning the nature of the dose–response relationship especially at low level exposures. The present paper assesses the occurrence of hormetic-like biphasic dose responses within the nanotoxicology literature. The findings indicate that nanoparticles may induce hormetic-like biphasic dose responses in a wide range of biological cell types, and that these responses can be highly dependent upon the physical and chemical properties of the agent. While the mechanistic foundations of hormetic dose responses induced by chemicals and pharmaceuticals have markedly advanced over the past decade, this remains an important data need for nanotoxicology.