Dendritic cells(DC) are a system of highly efficient antigen-presenting cells that initiate the primary immune response. There are two kinds of dendritic cells in the skin, Langerhans cell in the epidermis and dermal dendritic cell in the dermis. The knowledge of DC, which are very important in the immune reponse of cancer, autoimmune disease, transplantation and infection, has been known through the study about Langerhans cells. In this paper, the role of Langerhans cell in the contact hypersensitivity and atopic dermatitis is discussed and culture methods of mouse Langerhans cells and human U from pheripheral blood monocytes are described.