[en] The soil is the basic environment of migration of radionuclides into plants, from which they reach the people and animals through food. The type of soil affects the distribution of radionuclides in the soil itself and their transfer into plants, respectively. Systemic testing of radioactivity of soils is performed on specific locations in the Federal Republic of Yugoslavia, in particular time periods according to methods defined by regulations. As result of NATO aggression and use of ammunition with depleted uranium in 1999, the existing radioactivity monitoring program of Yugoslavia was modified. Besides measurement of activity of artificial radionuclides, that were present in living environment after Chernobyl accident in 1986, the testing of activity of natural radionuclides, especially of uranium, was carried out as well. Uranium in Serbia derives from natural sources, considering the geological composition of rocks and geochemical composition of soil, and their concentrations as well as the concentrations of its descendants represent the significant component of natural sources of ionizing irradiation. In Serbia, the major uranium sources are igneous, carbonic and sedimentary rocks, and granite. According to perennial geological investigation of uranium in our country, several geological regions have been found to have uranium in higher or lower concentration. The uranium concentration in these regions ranged from 0.003g/t for ultra basic rocks to 3.5g/t for igneous, sedimentary rocks and granite. One of considerable uranium sources is specific technological procedure in industry such as production and combustion of coal in thermal plants, production of phosphate mineral fertilizers, production of phosphoric acid, phosphoric plaster, etc