Background. Immunotherapy in elderly patients is controversial, and there is still not much evidences supporting this treatment's safety and efficacy in this population. This study was performed to evaluate the safety and efficacy of specific injection immunotherapy for house dust mite allergens in patients over 65 years of age with allergic rhinitis and a confirmed allergy to house dust mites. The primary endpoint was the change from baseline in the mean average adjusted symptom score (AAdSS) and the total combined rhinitis score (TCRS) difference in the least square means in the label in comparison to placebo.