Atopic dermatitis (AD) is a chronic inflammatory skin disease with a complex pathogenesis. It is clinically well-defined and represents one manifestation of the atopic state, along with asthma, food allergy and/or allergic rhinitis. Within the last several decades, there has been much evidence to support the contribution of immune mechanisms in the pathogenesis of AD. It has also been documented that the prevalence of all atopic disease, including AD, has been increasing, although the environmental factors that may be contributing to this increase are not clearly defined. A better understanding of the underlying immunopathogenesis of AD should aid in better clinical management and development of new treatment options.