Background The prevalence of allergic disease to be increasing across the world. More than 20 of the population worldwide suffer from diseases which mediated by immunoglobulin E, such as asthma, rhinoconjunctivitis, atopic dermatitis or eczema. There is no data about allergen sensitization of allergic disease in Manado.Objective The purpose of this study is to know the allergen sensitization in children with allergic diseases atopic dermatitis, allergic rhinitis, asthma . Children were divided into group less than and more than or equal to 3 years old, which was evidenced by skin prick test or IgE Atopy test in Prof. Dr. R.D. Kandou Hospital Manado.Methods This study was a descriptive cross sectional study, conducted from June until August 2016.Results A total of 95 children were included in the study, of which 77 children were ge 3 years old and 18 children were 3 years old. Seventy five children underwent skin prick test and 20 children underwent IgEAtopy test. In 3 years old children, there were 14 children diagnosed with atopic dermatitis and 4 children diagnosed with atopic dermatitis and asthma. In ge 3 years old children, the most common diagnosis was allergic rhinitis, as many as 21 children. Allergen sensitization found in 3 years old children with atopic dermatitis and atopic dermatitis asthma was cow rsquo s milk, house dust mites and egg white. Sensitization to house dust mites most commonly found in patients with atopic dermatitis. The most common allergen sensitization in ge 3 years old children was house dust mites, egg white, potatoes, dog fur, cow 39 s milk, wheat flour and soya formula.Conclusion The most common allergen sensitization in 3 years old children with atopic dermatitis is cow 39 s milk, while in children with asthma and atopic dermatitis is house dust mites, whereas in ge 3 years old children with atopic dermatitis, allergic rhinitis, asthma, or combination of the disease is house dust mites.