[en] The model of the formation of the internal doses for the population living on the territory contaminated after the Chernobyl accident is described. Model parameters were obtained on the base of natural measurements results implemented in the different terms after the accident. The data on the caesium radionuclides content in the bodies of the inhabitants measurements were priority for the internal exposure dose estimation. In the case of the absence of such information, the results of the radionuclides content in the food products analysis or the data on the soil types prevailing in the areas of settlements, were used for the calculations. The data were obtained during 1986-2001 as a result of monitoring of contaminated areas in Russia that considerably differ in their soil and climate conditions, the levels of 1^37Cs and 9^0Sr surface activity on soil and types of countermeasures applied. A summary of effective half-lives (T_1/2) of 1^37Cs and 9^0Sr aggregated transfer factors (Tag) from soil into agricultural and natural products observed after the Chernobyl fallout is given. The short term decrease of 1^37Cs Tag from soil into milk and beef during two months after fallout were observed - T_1/2 varied from 13 d to 36 d in depend on the part of dry and wet fallout. The studies between autumn 1986 and 1991 suggest a decrease in the 1^37Cs Tag with T_1/2/2 =1-2 years. From 5-6 years after deposition onwards T_1/2/2 of 1³⁷Cs and 9^0Sr Tag's in the range of 8 to 21 years were observed. Effective half-lives of 1^37Cs Tag's for foods from semi-natural ecosystems (mushrooms, berries, game, fish) are longer (up to tens years). On at least for some natural products the decrease seems to be only to radioactive decay. Comparison of the data on the dynamics of 1^37Cs content in agricultural and natural food products indicates that the contribution of the latter in the internal dose of population grows with each year after fallout, and can reach in the remote period up to 70 %. The influence of the actually applied measures for radiation protection of the population living in different zones of radioactively contaminated territories was taken into account. The results of the internal exposure doses estimations for the population in the different terms after the accident in condition of the countermeasures absence are given for a comparison. On the most contaminated territories these doses could exceeded actual in 5-7 times