Specific hyposensitization in 165 children with inhalant allergy was successful in 82.4%. Children with pollen-allergy showed statistically better results than those with other inhalant-allergies. In the latter group, the failure rate was significantly higher when polyvalent antigen-combinations were used. Age, and duration of the allergic disorder before therapy apparently have no significant influence on the therapeutic success. Children hyposensitized for more than one or two years achieved significantly better short-term results. Patients with atopic dermatitis showed worse results in both groups. Where there is no success after one year of therapy, antigen-determinations should be controlled by repeated cutaneous-vascular tests. In the non-pollen-allergies the prevalent antigen should be determined by provocation-tests. Longterm results after hyposensitization are less favourable than those shortly after a therapeutic course. Three years after discontinuation of therapy success diminished by 35.7%, the recurrence rate was higher in the 1st year than after 2 or 3 years. Frequent local and systemic adverse reactions demand a high responsibility of the physician performing the hyposensitization regimen. In pharmaceutical brochures up to 10,000 PNU are recommended, but this may result in dangerous overdoses.