INTRODUCTION: A few earlier studies have indicated that allergic rhinitis (AR) is under-diagnosed and under-treated. OBJECTIVE: To assess awareness, diagnosis and treatment of allergic rhinitis in a general population of Danish adults. METHODS: Between October 2007 and June 2008, a total of 1277 consecutive participants in a Danish general population study of 18-69-year-olds were skin prick tested and asked about respiratory symptoms. AR was defined as a combination of self-reported rhinitis symptoms and skin prick test reactivity against inhalant allergens. Participants reporting rhinitis symptoms completed an additional questionnaire on medication for rhinitis symptoms. RESULTS: The prevalence of AR was 23.1%. A total of 43.6% (n=122/280) of persons with AR had not received any treatment in the previous 12 months and only 56.6% (n=163/288) had been given a diagnosis of hay fever by a doctor. 48.5% (n= 143/295) reported both AR and lower airway symptoms indicating more severe AR. These persons were significantly more likely to having received treatment in previous 12 months and a diagnosis of hay fever. CONCLUSION: Our results support that even in an affluent country like Denmark AR is often un-diagnosed and un-treated. There appears to be a need for increased awareness of AR with regard to both diagnosis and treatment.