Nasal congestion due to the common cold may be exacerbated in small children because of their small nasal passages. Our aims were 1) to test the hypothesis that smaller children have relatively larger nasal airways compared to the intrathoracic airways, and 2) to examine the effect of stenting and a decongestant on nasal patency and nasal flow. During oral forced vital capacity (FVC) maneuvers, expiratory flow is limited by intrathoracic airways. During nasal FVC, flow at high volumes is limited by the nose. The point where the nasal flow-volume curve becomes superimposable on the oral curve (%Sup) depends on the relative resistance of nasal and intrathoracic airways. Fifty-four healthy children (28 male), median age 9.5 years (range 5.9-16.0), performed full forced respiratory maneuvers through: 1) the mouth, 2) the nose, 3) the nose after application of an external stent (Breathe Right (BR) strip), and 4) the nose following instillation of xylometazoline. Peak inspiratory and expiratory flow (PIF and PEF), and mid-inspiratory and expiratory flow (MIF50 and MEF50) all showed a significant decrease from the oral to the nasal baseline maneuver. Mean (SD) %Sup of the nasal baseline was 35.6 (13.7)% and was unrelated to height. PIF and MIF50 increased with the BR strip (P < 0.05). Xylometazoline also caused a significant increase in all measured flows (P < 0.05). Mean (SD) %Sup of the nasal maneuver after application of xylometazoline increased to 53.3 (14.0)%. We conclude that there is no evidence that relative resistance of nasal and intrathoracic airways change with height. The %Sup is easy to obtain and may prove a useful index of nasal patency.