Materials and methods. The study with double blind, placebo controlled trial was conducted in one centre. Fifty eight elderly patients with house dust mites allergy and AR were individually randomized in comparable numbers to one of two parallel groups: two years perennial AIT with the use Purethal Mites or placebo. Symptoms and medication score were presented as AAdSS and TCRS. Quality of life based on Rhinoconjunctivitis Quality of Life Questionnaire (RQLQ), serum allergen specific IgG4 to D.pteronyssinus and D. farinae and Der p1 and Der p2 were monitoring.