Abstract: Thy-1 positive dendritic epidermal cells (Thy-1⁺dEC) and Langerhans cells (LC) in the skin of various areas of young and old mice and rats were simutaneously investigated. It was demonstrated in C57 BL/6Ss mice that the Thy-1⁺dEC were usually bigger than LC, Thy-1 antigens were located mainly on the membrane of Thy-1⁺dEC, while Ia antigens distributed evenly in the LC; the dendrites of Thy-1⁺dEC were usually shorter than those of LC and sometimes even not distinct; on the surface of normal keratinocytes there was also a small amount of Thy-1 but no Ia antigens. Both cells were less numerous in the old than in the young animals. In Lewis/Ss and BN/Ss rats, no Thy-1⁺dEC were seen. We suggest the Thy-1⁺dEC might have immunologic functions. Further search for the human analogue of the murine Thy-1⁺dEC might offer a new aspect of studies on mechanisms of cutaneous disorders.