This report provides an overview and analysis of the knowledge, concerning exposure to ultraviolet radiation (UV), and the risks associated with UV-exposure. Sources of UV are found in the outdoor environment, in the indoor environment, an in medical therapies and labour situations. Although limited information is available of UV- exposure, it is very likely that the exposure increases. UV-exposure can lead or contribute to a variety of deleterious effects, among which sunburn and snowblindness shortly after irradiation, and skin cancer, skin ageing, cataract formation and selective suppression of immuneresponses after prolonged exposure. In the environment increasing UV-exposure levels could lead to a decrease in the production of biomass in terrestrial and aquatic ecosystems, with possibly negative implications for the foodweb and influence on the biodiversity of ecosystems. The quantitative risk assessment is presently only possible for skin cancer, and to a lesser degree for cataract formation. The report summarizes a number of research priorities which can contribute to support policymakers.