There is still much controversy in scientific approaches to setting limits of exposure to radio-frequency electromagnetic radiation in Russia, Europe and USA. The stumbling stone is recognition or denial of potential risk of biological effects from nonthermal electromagnetic radiation (to 1 mW/cm2). The authors review results of experimental investigations performed in Russia over the years since 1960s to study the direct and delayed effects of ultra-high and microwave frequencies of low non-thermal intensity EMR, and delayed negative effects in employees based on the data of several follow-up epidemiological studies. This evidence was used as a baseline for establishing the Russian limits for chronic exposure to, thresholds of harmful effects and the maximal admissible values of EMR within the above frequencies.