A large-scale study conducted in Belgium, France, Germany, Italy, Spain, and the UK estimated the prevalence and diagnosis rate of allergic rhinitis in Europe. The study involved two steps: a telephone interview to screen for allergic rhinitis based on symptoms and self-awareness, followed by clinical confirmation in selected centres. A total of 9,646 telephone interviews were conducted, with 19% of subjects reporting self-awareness of allergic rhinitis and 13% having a physician-based diagnosis. In step two, 725 clinical assessments were performed, confirming 411 cases of allergic rhinitis. Of these, 45% had not been previously diagnosed by a physician. Combining step one and two data, the prevalence of clinically confirmable allergic rhinitis ranged from 17% in Italy to 29% in Belgium, with an overall value of 23%. The study confirmed that allergic rhinitis is common in western Europe and is frequently undiagnosed. The prevalence of self-awareness was close to that found in the European Community Respiratory Health Survey (ECRHS), which reported 21% overall. The study also found that 45% of subjects with allergic rhinitis were undiagnosed, a figure consistent with previous studies. The new ARIA classification was used to categorize allergic rhinitis as persistent or intermittent. The study found that 31% of diagnosed subjects were unaware of their condition, and 45% had not been previously diagnosed. The prevalence of allergic rhinitis was estimated to be 22-23% in the general population, with a higher rate in northern countries. The study highlights the need for improved diagnosis and treatment of allergic rhinitis, as undiagnosed cases may have less severe symptoms but still benefit from proper management. The study was funded by UCB Pharma and was conducted in accordance with ethical standards.A large-scale study conducted in Belgium, France, Germany, Italy, Spain, and the UK estimated the prevalence and diagnosis rate of allergic rhinitis in Europe. The study involved two steps: a telephone interview to screen for allergic rhinitis based on symptoms and self-awareness, followed by clinical confirmation in selected centres. A total of 9,646 telephone interviews were conducted, with 19% of subjects reporting self-awareness of allergic rhinitis and 13% having a physician-based diagnosis. In step two, 725 clinical assessments were performed, confirming 411 cases of allergic rhinitis. Of these, 45% had not been previously diagnosed by a physician. Combining step one and two data, the prevalence of clinically confirmable allergic rhinitis ranged from 17% in Italy to 29% in Belgium, with an overall value of 23%. The study confirmed that allergic rhinitis is common in western Europe and is frequently undiagnosed. The prevalence of self-awareness was close to that found in the European Community Respiratory Health Survey (ECRHS), which reported 21% overall. The study also found that 45% of subjects with allergic rhinitis were undiagnosed, a figure consistent with previous studies. The new ARIA classification was used to categorize allergic rhinitis as persistent or intermittent. The study found that 31% of diagnosed subjects were unaware of their condition, and 45% had not been previously diagnosed. The prevalence of allergic rhinitis was estimated to be 22-23% in the general population, with a higher rate in northern countries. The study highlights the need for improved diagnosis and treatment of allergic rhinitis, as undiagnosed cases may have less severe symptoms but still benefit from proper management. The study was funded by UCB Pharma and was conducted in accordance with ethical standards.