Background and Objectives Nitric oxide (NO) is present in high concentrations in the upper respiratory tract. The physiological role of this mediator is to contribute to the local host’s defense, modulate ciliary motility and serve as an aerocrine mediator in helping to maintain adequate ventilation-perfusion matching in the lung. Subjects and Method The purpose of the study was to assess the relationship of nasal NO (nNO) and exhaled NO (eNO) in nasal airway disease patients. NO concentration was measured using a chemiluminescence analyzer. nNO was analyzed by aspiration at a sampling flow rate of 700 mL/min with velum closure. eNO was analyzed during expiration against a constant resistance of 10 cm H2O. Results NO concentration of the normal control group (n=32) was compared with that of the allergic rhinitis group (n=31) and the rhinosinusitis with that of the nasal polyp group (n= 30). The mean nNO level in the control group was 241±89 ppb and eNO was 20.5±6.4 ppb. The mean nNO level was significantly increased in the allergic rhinitis group (332±125 ppb) but decreased in the chronic sinusitis group (89±55 ppb). The mean eNO level was significantly increased both in the allergic rhinitis group (26.9±10.1 ppb) and chronic sinusitis group (29.8±12.8 ppb). Conclusion nNO concentration was increased in patients with allergic rhinitis and decreased in patients with chronic sinusitis; however, eNO was increased in both patients. This shows that patients with upper respiratory inflammation may also have lower respiratory inflammation, supporting the concept of ‘one airway, one disease’. This study shows that measurement of NO is useful for the study or evaluation of nasal diseases.