Introduction: Allergic rhinitis (AR) is an increasingly prevalent worldwide disease, which has an important impact on quality of life and generates high social and health care costs. The ARIA classification, that considers both the duration and severity of AR, seems more appropriate than previous classifications of AR, but few studies exist on the validation of the severity criteria proposed by the ARIA classification. Objectives: To assess the ARIA duration and severity classification of AR in a large sample population of patients, by investigating whether different degrees of severity correlate with differences in symptom score, quality of life or the patient's self evaluation of impairment. This study also assesses the relationship between AR severity and comorbidities. Material and Methods: An observational, cross-sectional, multicentre study conducted in Spain. AR was classified based on the ARIA criteria, and compared to the classical classification based on allergen exposure. Rhinitis was evaluated by the Total 4-Symptom Score (T4SS) scale, quality of life was measured using the Rhinoconjunctivitis Quality of Life Questionnaire (RQLQ), and disease severity through a Visual Analogue Scale (VAS, 0-100 mm). Comorbidities were evaluated based both on the duration and severity of the symptoms of rhinitis. Results: AR patients, (n = 3,529; mean age 37.5 +/- 13.4 years.; 52.3% women) were included in the study. AR patients were classified as intermittent (51.5%) and persistent (48.5%) based on the ARIA classification, and as seasonal (61.2%), perennial (35.1%), and occupational (3.7%) based on the allergen exposure classification. Significantly higher T4SS, RQLQ and VAS scores were obtained in moderate/severe compared to mild AR. The incidence of asthma was significantly higher in patients with persistent and moderate/severe AR compared to intermittent and mild AR. Asthma was the only comorbidity to reach statistical significance. Conclusion: ARIA classification of severity reflects two different statuses of AR in terms of symptoms and quality of life. Asthma was the only concomitant pathology in which incidence was related to ARIA categories in terms of duration or severity.