Monitored Natural Attenuation (MNA) is becoming more and more accepted in agrowing number of European countries. So far, there is no common approach for the use of MNA in Europe. Some countries already have national guidelines/regulations in place accounting for country-specific environmental requirements. The fundamental processes behind NA are summarized and the common methodology for the application of MNA in thefield is presented. Examples of URS-related experience with MNA in a variety of European countries are given.