Abstract During the last 50 years, a large amount of information on radionuclide accumulators or “sentinel-type” organisms in the environment has been published. Much of this work focused on the risks of food-chain transfer of radionuclides to higher organisms such as reindeer and man. Until the 1980s and 1990s, there were few published data on the radiocesium ( 134Cs and 137Cs) accumulation by mushrooms. The present review of published data for 134,137Cs accumulation by mushrooms in nature discusses the aspects that promote 134,137Cs uptake by mushrooms and focuses on mushrooms that demonstrate a propensity for use in the environmental biomonitoring of radiocesium contamination. Transfer factors (TF, as dry weight concentration in fruiting body divided by concentration in substrate) ranged up to 24 (unitless), and aggregate transfer factors ( T ag, as Bq 137Cs/kg dw in fruiting body divided by the aerial deposition as Bq/m 2) ranged up to 8 m 2/kg dw.