Distribution of resistance to respiratory airflow in the nasal cavities was determined by digitized pressure/flow measurements of consecutive 2-cm airway segments between nostril and nasopharynx. Healthy adult subjects seated in a head-out body plethysmograph breathed exclusively through a single nasal cavity while transnasal pressure and flow signals were transduced, digitized and processed by a programmed desk-top computer to provide resistance values. Mean total resistances of untreated and decongested single nasal cavities were 0.44 (n = 30; SD +/- 0.25) and 0.26 (n = 15; SD +/- 0.06) Pa/cm3/s, respectively. The proportion of total airway resistance of successive 2-cm segments from nostril to nasopharynx was 56%, 22%, 16%, and 6% in the untreated nose, and 88%, 5%, 2%, and 5% following decongestion. The findings from 45 nasal cavities are consistent with previous pressure/flow measurements from six nasal cavities and support recent acoustic reflection assessments of nasal cross-sectional areas of both untreated and decongested noses.