Atopic dermatitis (AD) is a chronic inflammatory skin disease that is characterized by pruritic and eczematous lesions and is associated with elevated serum IgE levels and tissue and peripheral blood eosinophilia. AD is characterized by the predominat infiltration of Th2-type cells, especially in the acute phase of lesional skin. Chemokines are small secreted molecules that regulate leukocyte trafficking. TARC / CCL17 and MDC / CCL22 are ligands for CCR4 which is specifically expressed by Th2 cells. Eotaxin-3 / CCL26 is a ligand for CCR3 which is preferentially expressed on eosinophils. CTACK / CCL27 is expressed only in the skin, a ligand for CCR10 and selectively chemoattracts CCR10-positive memory T cells to the inflammatory sites. MEC / CCL28 is strongly expressed in mucosal epithelial surfaces, a ligand for CCR10 and CCR3, and attracts subsets of memory T cells and eosinophils. We have clarified that serum levels of several chemokines such as TARC, MDC, eotaxin-3, CTACK and MEC reflect the disease activity of AD. We also investigated serum TARC levels in patients with bullous pemphigoid (BP), which is a blistering autoimmune skin disease, and mycosis fungoides (MF), which belongs to cutaneous T-cell lymphoma, and various other skin diseases. Serum TARC levels also reflect the disease activity of BP and MF. We confirmed that these levels sharply reflect disease activity in a large number of AD patients. Of note is that very high serum TARC levels are only seen in a limited number of skin diseases. Serum TARC levels may thus be a useful laboratory marker for the diagnosis of AD, especially moderate to severe cases, and for the evaluation of disease activity of AD.