PURPOSE: We investigated the change in serum total immunoglobulin E (IgE) and allergen-specific IgE according to allergic diseases and age. METHODS: Allergic markers of children under 18 years of age with allergic diseases for the last 5 years were collected from 12 hospitals nationwide. The total data was 9,710. Data about levels of serum total IgE and allergen-specific IgE to 15 common allergens were collected. RESULTS: In children with asthma, serum total IgE was higher in older age than in younger age until age 7 to 12 years, at which time the level was highest (paper radioimmunosorbent test, 526.7 IU/mL; UniCAP, 339.9 IU/mL). The level was lower in older age than that during younger age. This change was similar to that in children with allergic rhinitis and atopic dermatitis. The level was highest at ages 7 to 12 years in children with allergic rhinitis, and at age 10 to 12 years in children with atopic dermatitis. In children with both asthma and allergic rhinitis, as well as in children with all three diseases, the change in serum total IgE was similar to that of children with an isolated disease. The highest level in children with all three diseases was higher than that in children with an isolated disease. The analysis of allergen-specific IgE positivity showed that food allergens were dominant before the age of 2 years, and that aeroallergens such as house dust mites were dominant. CONCLUSION: Serum total IgE in Korean children with allergic diseases was higher in older age than in younger age until the ages of 7 to 12 years, and then the change in total IgE by age was the opposite.