PURPOSE: Few studies have demonstrated the effects of aeroallergen sensitization on the development of atopic dermatitis (AD) in young children. This study aimed to investigate the sensitization rate of food and aeroallergens in AD patients under 2 years of age and to compare clinical characteristics between IgE- and non-IgE-mediated AD patients. METHODS: Children aged less than 2 years who had visited CHA Bundang Medical Center from 2013 through 2016 were enrolled. Allergen sensitization was measured by specific IgE levels for common allergens. Detailed information was obtained using an atopy questionnaire. RESULTS: A total of 173 patients were examined, 118 (68.2%) were male patients. The prevalence of aeroallergen sensitization under 1 year of age was 4.8% and increased to 19.5% for children aged 2 years (P=0.005). The mean age (13.6±6.3 months vs. 9.0±5.1 months, P=0.003) and the proportion of children born prematurel (15.4% vs. 2.3%, P=0.013) were higher in the aeroallergen-sensitized group than in nonsensitized group. Sensitization to food allergens between children aged less than 1 year and 2 years appeared to be similar (61.1% vs. 57.1%, P=0.651). There were no significant differences in clinical characteristics between food allergen IgE-mediated and non-IgE-mediated AD children. CONCLUSION: Aeroallergen sensitization increased markedly in AD patients aged 2 years which is about 4 times that of the general population. However, there were no significant differences in clinical manifestations between allergen IgE-mediated and non-IgE-mediated AD children in both food and aeroallergens.