Objective: Many patients with allergic rhinitis (AR) have bronchial hyper-responsiveness (BHR), and seasonal variation of BHR has been demonstrated in these patients. We aimed to investigate how BHR in children with seasonal AR is modified by triamcinolone acetonide aqueous nasal spray (TANS) therapy during the pollen season. A secondary aim was to assess the efficacy of TANS on nasal congestion by acoustic rhinometry and symptom scores. Methods: A total of 34 children aged 7-18 years with grass pollen-induced AR and 18 age and sex-matched healthy controls were included in study. The patients were divided into the following two subgroups: 22 patients who had AR only; and 12 patients who had AR and asthma. All of them had a baseline BHR (PC20FEV1 methacholine <8 mg/ml). AR patients received 220 mug TANS once daily for 4 weeks following a 1-week run-in period. Nasal patency was measured by acoustic rhinometry and patients recorded their nasal obstruction scores in a diary. Results: There was no significant difference at baseline pulmonary function test parameters between the patients and the healthy control children. None of the control subjects had BHR. Asthmatic children with AR had significantly reduced baseline PC20FEV1 when compared with the AR only group [mean +/- S.E.M., (1.60 +/- 0.57 mg/ml. versus 2.93 +/- 0.42 mg/ml, P = 0.021)]. The mean PC20FEV1 values increased slightly at the end of treatment in both group (from 1.60 +/- 0.57 mg/ml to 3.25 +/- 1.11 and from 2.93 +/- 0.42 mg/ml to 3.93 +/- 1.41 mg/ml), but the change was not statistically significant. TANS produced substantial symptomatic recovery in nasal obstruction according to patients' daily diary assessments, and significantly improved all objective acoustic rhinometry parameters. Conclusions: Once-daily intranasal TANS 220 mug effectively controlled nasal obstruction in children with seasonal AR according to subjective and objective assessments, and blocked the increase in BHR to methacholine after high-toad natural pollen exposure. There was no correlation between patients' own subjective assessment of nasal obstruction and objective acoustic rhinometric assessment. (C) 2004 Elsevier Ireland Ltd. All rights reserved.