With the rapid development of nanosciences and nanotechnology, a wide variety of manufactured nanomaterials are now used in commodities, pharmaceutics, cosmetics, biomedical products, and industries. While nanomaterials possess more novel and unique physicochemical properties than bulk materials, they also have an unpredictable impact on human health. In the pharmacology and toxicology studies of nanomaterials, it is essential to know the basic behavior in vivo, i.e. absorption, distribution, metabolism, and excretion (ADME) of these newly designed materials. Radiotracer techniques are especially well suited to such studies and have got the chance to demonstrate their enchantment. In this paper, radiolabeling methods for carbon nanomaterials, metallic and metal oxide nanoparticles, etc. are summarized and the applications of the radiolabeled nanomaterials in pharmacology and toxicology studies are outlined.