Abstract <p>The levels of accumulation of long-lived radionuclides ⁹⁰Sr and ¹³⁷Cs were studied in the marsh frog <i>Pelophylax ridibundus</i> Pall., 1771, inhabiting the lakes Alabuga and Kuyash located in the peripheral zone of the East Ural Radioactive Trace (EURT). The concentration of ⁹⁰Sr in the frogs from Lake Alabuga varies from 50 to 200 Bq/kg; in Lake Kuyash, from 100 to 320 Bq/kg of dry weight of animals. The content of ¹³⁷Cs in the frogs from lakes Alabuga and Kuyash changes from 5 to 35 and from 35 to 145 Bq/kg of dry weight, respectively. The levels of concentrations of the studied radionuclides in the same type of components of the reservoirs of the EURT and the reservoirs of the Middle Urals are compared. It has been shown that the content of 90Sr in frogs of lakes Alabuga and Kuyash per dry body weight exceeds the intervention level for fish according to accepted standards (SanPiN dated April 15, 2003).</p>