Abstract: The Langerhan's cell (LC) density was assessed in guinea pig epidermis treated with chronic ultraviolet irradiation. It was found that the epidermal LC density was siginificantly reduced in the irradiated site of the treated animals in comparison to oontroi animals, F-Qtest being siginificantly different. However, during the different irradiated stages, Goth in the irradiated site of the treated animals or conWol animals there were no siginificant difference in their epidermal LC densities; but in the unlrradiated site of the treated animals, with the increase of the irradiated tune, the LC density was gradually decreased and approached the irradiated site. Additionally, as mentioned in the previous article, the histological alterations in the guinea pig skin treated with chronic ultraviolet irradiation were also similar to those in the photoaged human skin. We therefore consider that the reduckion of LC density in the present study is a component of cutaneous photoaging.