Nanotechnology is an extremely diverse and multi–disciplinary field, ranging from novel extensions of conventional physics to completely new approaches based upon molecular self–assembly, to developing new materials and machines with nanoscale dimensions. Nanotechnology deals with structures in the range of 1–100 nm and focuses on the development of materials with novel properties often not present in nature. As a result, it is considered as a key technology of the twenty–first century and promised to deliver innovative methods to medicine and dentistry. It is expected that nanotechnology will have a major impact on medicine and health care; energy production and conservation; environmental clean–up and protection; electronics, computers, and sensors; and world security and defense. This review focuses on the impact of nanotechnology on the major public health problems and the issues concerned with use of nanotechnology in the health sector.