Atopic dermatitis (AD) and hypogammaglobulinemia are 2 entities that appear during early childhood. Some studies report that atopy and atopic diseases are frequent among children with low immunoglobulin [Ig] levels. The aim of the study was to define the characteristics of children with both AD and low serum Ig levels. One hundred and twenty-five AD patients under 4 years of age who had low serum Ig levels were compared with their peers with normal Ig levels, in terms of age, gender, parental consanguinity, exposure to smoke, breastfeeding, personal and familial atopy, IgE level, peripheral eosinophil content, and disease severity. Consanguinity of parents and other allergic diseases were more common among children with normal Ig levels. Serum IgE levels were lower among patients with low Ig levels. Disease severity was not different between the groups. When low for age, serum IgA and IgM levels are related to the severity of AD. Hypogammaglobulinemia can coexist with AD in young children. The level of Ig deficiency may affect AD severity. Larger prospective studies are needed for better understanding the effect of hypogammaglobulinemia on AD and for developing better management strategies for patients who have both conditions together.