Nanotoxicology is an emerging new multidisciplinary field of science. This new technology deals with measures, manipulates, and manufactures at the atomic, molecular, and supramolecular levels, aimed at creating materials, devices, and systems with fundamentally new molecular organizations, properties, and functions associated with greater strength, stability, chemical and biological activity. They are used in rapidly increasing nanoproducts, nanodevices, electronics, diagnostics and drug delivery systems. They are present in a variety of consumer products such as foods, drugs, cosmetics, food colour additives, food containers, paints and surface coatings. Because of their extremely small size they are capable of entering the human body by inhalation, ingestion, skin penetration, intravenous injections and medical devices, and have the potential to interact with intracellular macromolecules. Because of their greater stability they are anticipated to remain in the body and in the environment for long periods of time. However, information on their potential adverse health effects is very limited at the present time. It is not known at what concentration or size they can exhibit toxicity. Therefore, there are obvious public safety concerns. This has led to the initiation of a new research discipline commonly known as Nanotoxicology. The current review article reveals the concept of Nanotoxicology from nanomedicine and nonmedical nanoparticles.