An association between nasal allergy and loss or diminution of olfaction has been noted frequently in literatures, and patients' complaints of olfactory loss are not uncommon to allergists. Although it is not a life-threatening condition, chronic impairment of olfaction can significantly affect an individual's sense of well-being. However, the impact of allergic rhinitis on sense of olfaction in the absence of other nasal abnormalities has not been studied extensively. The purpose of this study is to assess the olfactory function in patients with allergic rhinitis and to evaluate the relationship between olfactory threshold and nasal airway patency and also to evaluate the effect of sinusitis on olfactory threshold in patients with allergic rhinitis. The subjects were 108 patients with allergic rhinitis, and we checked and compared T & T olfactometer, peak nasal inspiratory flow(PNIF)meter and PNS views. The results were as follows : 1) Patients with allergic rhinitis showed significantly higher olfactory threshold than normal control. 2) Nasal airway patency was significantly lower in patients with allergic rhinitis than normal control. 3) Patients with allergic rhinitis and sinusitis showed higher olfactory threshold than patients with allergic rhinitis and not sinusitis. 4) There was no overall correlation between olfactory threshold and nasal airway patency in patients with allergic rhinitis. But in patients with olfactory disturbance, there was a significant correlation between olfactory threshold and nasal airway patency. In conclusion, nasal obstruction alone cannot fully account for olfactory loss in patients with allergic rhinitis, and sinusitis may underlie many causes of allergy-related olfactory disurbance.