Abstract: Atopic dermatitis (AD) is an inflammatory disorder of the skin characterized by impaired immune response. Th9 cells are a sub-population of T cells that release interleukin (IL)-9. No study has investigated the role of IL-9 in AD. This study compared 64 children with AD with 45 healthy children. Serum IL-9 levels were measured and clinical symptoms were assessed. Children with AD had higher serum IL-9 levels than controls (p = 0.01). Clinical severity was significantly related to IL-9 level, indicating that IL-9 might exert a pathogenic role in symptom occurrence in individuals with AD. Children with AD may have higher serum IL-9 levels than healthy children, and IL-9 levels are significantly related to symptom severity.