The incidence of allergic diseases has increased worldwide. Thus, there is a need for effective primary prevention of allergies.The aim of the present study was to examine how allergen-specific immunotherapy (ASIT) affects the development of allergies in the generation of children whose parents were subjected to this method of treatment.A total of 194 children with at least one parent with allergy subjected to ASIT were enrolled. These patients were compared with control individuals without ASIT. Their risk of allergy, based on medical history, examination, allergy skin-prick tests, serum total immunoglobulin E and specific immunoglobulin E concentrations was assessed.The children of parents subjected to immunotherapy showed significantly reduced clinical symptoms of allergic disease. The odds ratios (OR) of any allergic disease and asthma were significantly lower in children with one or both parents with allergy after ASIT compared with the children with parents with allergy and without ASIT: OR 0.73 (95% confidence interval [CI], 0.59-0.86) versus OR 1.85 (95% CI, 1.73-2.2) for any allergic disease and OR 0.63 (95% CI, 0.53-0.79) versus OR 1.36 (95% CI, 1.22-1.67) for asthma.The phenomenon of reducing the risk of allergies in children whose parents were desensitized might be important in the primary prevention of allergies.