Background: Asthma and rhinitis are frequent respiratory diseases in children and adults. Despite the increase in the aging population, there are few epidemiologic data on both diseases in the elderly. So far, no population-based study has analyzed the association between asthma and rhinitis symptoms and severity in this age group. This study aimed to estimate the prevalence of physician-diagnosed asthma in the population aged >= 65 years in mainland Portugal and to evaluate its association with the presence and classification of rhinitis according to ARIA recommendations, in this age group. Methods: A cross-sectional, nationwide, population-based survey of individuals aged >= 65 years, living in mainland Portugal was performed. Results: Data were obtained from 3678 respondents. The prevalence of physician-diagnosed asthma was 10.9\% (95\% confidence interval (95\%CI) 9.9-11.9). The frequency of asthma diagnosis increased with the number of nasal symptoms (p < 0.001). A strong association between asthma and rhinitis was found (odds ratio (OR) 13.86 (95\%CI 10.66-18.02)). The strength of this association increased with the persistence and severity of rhinitis, being particularly high in elderly subjects with moderate-severe persistent rhinitis (OR 39.9 (95\%CI 27.5-58.0)). Conclusions: Asthma is common in the elderly and strongly associated with rhinitis. The OR for asthma is especially high in persistent and severe ARIA classification rhinitis types. This study strengthens the need for an integrated assessment of asthma together with rhinitis in the elderly. (C) 2014 Elsevier Ltd. All rights reserved.