Photochemical techniques for the modification of polymer surfaces have been established as an alternative to corona and plasma treatments. In this review current research on photochemical modifications of polymer surfaces is reviewed. The review is focused on UV processes involving reactive gases and modifiers (halogens, pseudohalide compounds, ozone, hydrazine, boron compounds, sulfur dioxide, organic azides and others). Common UV and VUV light sources as well as reaction mechanisms of photomodification processes are considered. In addition, the applications of surface modified polyolefins (PE, PP), poly(ethylene terephthalate) (PET), fluorocarbon polymers (PTFE, FEP) and other polymers in the fields of coatings technology, biomedicine and electroless plating are surveyed (153 references).