Aim: Atopic dermatitis (AD) is the most common chronic skin disease of childhood. Although eczema may be a prominent finding in some primary immune deficiencies, there are very few studies conducted on the frequency of hypogammaglobulinemia in patients with eczema. In our study, we aimed to determine the frequency of hypogammaglobulinemia in patients with AD and the relationship between immunoglobulin levels and eczema severity. Materials and Methods: Patients between the ages of 0-18 years, who were diagnosed with AD between January 2015 and August 2018 in the Department Pediatrics Division of Pediatric Allergy and Immunology, Trakya University Faculty of Medicine, were included in the study. Hypogammaglobulinemia was defined as being less than -2 standard deviation of immunoglobulin A, M and G from normal values for age. Results: The median age of 117 patients included in the study was 11 months [interquartile range (IQR): 6.7-33 months], the median age of eczema onset was 3.5 months (IQR: 2-6 months), the median SCORingAtopicDermatitis at presentation was 13.8 (IQR): 5-32]. Thirty-six (30.8%) patients had low levels in one of the immunoglobulin isotypes and decreased levels of immunoglobulin A (IgA), M and G were found in 21 (17.9%), 18 (15.5%) and 23 (19.7%) patients, respectively. While there was no difference between mild and moderate-severe eczema groups in terms of ageat presentation, age of onset of eczema, family history of allergic diseases, smoking exposure, aeroallergen sensitivity, food allergy, the number of patients having hypogammaglobulinemia, and the levels of IgA, M and G, a male predominance and higher number of eosinophils were observed in the moderate-severe eczema group. Conclusion: It is concluded that the evaluation of immunoglobulin levels independent of the severity of eczema is important for the distinction of primary immunodeficiency and the follow-up of patients in terms of transient hypogammaglobulinemia of infancy in patients with AD