Herbert Hönigsmann, MD of the Medical University of Vienna, Vienna, Austria outlines his talk sun protection held at the World Congress on Cancers of the Skin (WCCS) and the Congress of the European Association of Dermato-Oncology (EADO) in Vienna, Austria. Prof. Hönigsmann first talks about the compounds that reflect or absorb ultra violet (UV) radiation and the question of factors, which are based on determing the ericema reaction. He further talks about the importance of UVA protection and UVB protection. Then he discusses the question if sun screen really protects against skin carcinoma development. From animal studies, we know sun screen can protect from tumor formation, in particular squamous cell carcinoma but the problem is that there are not very many human studies according to Prof. Hönigsmann. The most important human study was done in Australia, called Nambour study, which showed that there is a reduction of actinic keratoses and squamous cell carcinoma but no clear effect on basal cell carcinomas.