[en] Carried out are investigations on finding and comparative estimation of effective nutritive agents and nutritive additions which would reduce absorption and deposition in the organism of the most hygienically important radionuclides - cesium-137 and strontium-90 and increase resistance to chronic intake. In 3 series of experiments on 330 puberal rats (females) during 500 days studied are the effect of different diets on accumulation of these isotopes, weight dynamics, the state of wool cover, lifetime and quantity of neoplasms to the end of investigations. The animals daily have got 5x10^-7 Ci¹³⁷Cs and 2.5x10^-7Ci⁹⁰Sr. It is shown that changes in diet lead to reduction of accumulation of ¹³⁷Cs and ⁹⁰Sr in the rat organisms. Established is favourable effect of methionine which has reduced lethality of the animals and prevented their death from neoplasms