The epidermal Langerhans cells (ELC) are thought to be the outermost station of the immune system. Their location in the suprabasal layer of the epidermis makes them susceptible to a continuous exposure to ultraviolet irradiation (UVR) and if UVR alters the ELC, this may in turn induce both local and systemic effects. In this paper we have shown that UVA and UVB exposure produced dose-dependent changes of ELC, characterized by disturbance of spatial distribution and aggregation of the ATPase loci located in the ELC cytomembrane after low-dose exposure (1-3 MED), and actual cytomembrane damage after high doses (4-6 MED). UVC exposure, on the other hand, produced effects that were different from those of both UVA and UVB: high UVC doses, in fact, even though able to induce ELC morphological changes, failed to significantly reduce their number. These findings provide ultrastructural evidence of the deleterious effects produced by UVR on ELC.