This articles reviews the mathematical models of deposition and disposition of drugs administered into the human nasal cavity for systemic activity. The modeling of the disposition kinetics includes drug release from carriers, translocation within the nasal cavity and into the gastrointestinal tract, drug decomposition, and drug absorption during the transit through the nose and the gastrointestinal tract. The uses of such mathematical models for design and analysis of nasal delivery systems are illustrated, with particular reference to the new therapeutic materials and excipients. (C) 1998 Elsevier Science B.V.