Nanotechnology is a multidisciplinary scientific field that deals with the formulation, preparation, characterization and application of structures, devices and systems at nanometric scale. Area of concern is interdisciplinary, but with peculiarities, among others, medicine, pharmacy, biophysics, electronics, bioengineering, and molecular biology. Interest for modern nanotechnology lies in the creation and use of structures which have new properties because of their small size as well as the possibility of using these systems to control or manipulate biological structures at nanometric or atomic level. It will open the way to diagnosis and medical treatment to molecular level. This paper covers various fundamental and applied aspects of nanotechnology, in its chapters: introduction; nanoparticles (therapeutic polymers, polymeric nanoparticles, non-polymeric nanoparticles, liposomes, nanodevices) nanopharmaceutical systems used in diagnosis and therapy, in tissue engineering; pharmacokinetics and toxicity of nanoparticulate systems. Nanoparticulate systems have the potential to constitute a new generation of drug delivery systems. By their nature, nanodevices can be used as innovative diagnostic tool for detecting and monitoring disease, also for its treatment and use in developing new drugs.