The biophysics of nasal airflow involve the measurement, analysis, and understanding of bulk airflow or momentum transport through the nasal cavity and of the exchange of mass and heat laterally between the air stream and the walls. In both of these areas, optimal progress depends on judicious, combined, and continuous use of physical models, mathematical calculations, and measurements made on human subjects. The progress that has been made to date is both fascinating and encouraging and suggests that great improvement in understanding, diagnosis, and treatment of nasal and upper airway disease will be possible in the future through closer contact and cooperation between clinicians and physical and biological scientists.