Recent studies have demonstrated the association between allergic diseases and vitamin D deficiency. In addition to its classical role in calcium homeostasis, vitamin D has been known for its effect on immunomodulation. Because immunologic mechanisms play a role in the pathogenesis of atopic dermatitis (AD), vitamin D may influence the activity of AD. Epidemiological studies, clinical studies, and in vitro studies have suggested that vitamin D may improve the symptoms of AD. The purpose of this paper is to review the present literature that suggests a potentially significant role for vitamin D in AD. (Allergy Asthma Respir Dis 2013;1:197-202)