PURPOSE: Skin reactivity to different allergens may vary with age, since the degree and type of sensitization may be related not only to genetic factors but also to the intensity and duration of exposure to the allergens. The aim of this study was to evaluate profile of sensitization to airborne allergens according to age in children with allergic asthma. METHODS: We performed skin prick tests with 12 common airborne allergens in children with clinically diagnosed asthma, and analyzed the results of 313 patients with at least one positive response. Patients were arbitrarily divided into four groups, according to their age: group I(3 to 7 yrs; n=80), group II(7 to 10 yrs; n=93), group III(10 to 13 yrs; n=85), and group IV(13 to 17 yrs; n=55). The allergens tested were grouped into 5 classes : house dust mites, cockroach, animal danders, molds, and pollens. Atopy index and class index were calculated as the number of allergens and classes to which responses had been positive, respectively. RESULTS: In all groups, the most common positive allergic reaction was to house dust mites. Positive reactions to cat fur, mugwort, and ragweed among the allergens, and animal danders and pollens among the classes, tended to increase from group I to group IV(P<0.05). Atopy index increased with age(P<0.05). Class index also increased with age(P<0.05). Sensitization to more than one class of allergens occurred in 62.3% of the patients, and the percentage of these polysensitized patients tended to increase from group I to group IV(P<0.05). CONCLUSION: In children with allergic asthma, the positive number of allergens and their classes by skin prick test increased with the age of the patients. This phenomenon was associated with age- related increase in the frequency of polysensitized patients.