Allergic rhinitis (AR) and asthma coexist frequently and a dual treatment is recommended by prescribing topical nasal plus oral inhaled corticosteroids. The purpose of this study was to assess the efficacy of a nasally inhaled corticosteroid aiming at concomitant control of AR and asthma. A controlled trial was conducted among 60 patients with AR and asthma, aged 6-18 years, who were randomized into two groups. During 8 weeks, the experimental group (30 patients) received exclusively fluticasone proprionate hydrofluoroalkane (FP-HFA) inhaled through the nose (mouth closed) using a large volume spacer attached to a face mask. The comparison group (30 patients) received a nasal spray of isotonic saline plus oral inhalation of FP-HFA through a mouthpiece attached to the same spacer. Clinical scores for AR and asthma, nasal inspiratory peak flow (NIPF), and spirometry were assessed by blinded observers. There was a significant improvement in AR scores and NIPF in the experimental group (P = 0.001) up to week 8, when a worsening was observed after the intervention was interrupted. Asthma symptoms score, forced expiratory volume (FEV)1, and FEF25-75 percent were not statistically different between groups at the baseline visit or along follow-up visits (p=0.20). Prebronchodilator FEV1 (percent predicted value) improved by 10 percent in both group, comparing values at inclusion with those obtained at the end of follow up. Our results suggest that nasally inhaled FPHFA through a spacer may control AR and asthma in children and adolescents. This approach is likely to result in higher compliance, lower costs, and fewer side effects.