Using different algea types the bioaccumulation of UO22+and Th4+ions from experimental residual wastes of nuclear facilities was investivated. The retaining degree of these ions on microbiological sorbents decreases as:Scenedesmus quadricauda>Porphyridium cruentum>Spirulina platensis>Calothrix sp.2>Calothrix sp.1for UO22+andPorphyridium cruentum>Spirulina platensis>Scenedesmus quadricauda for Th4+. For the same algae it was observed that the retaining degree is much higher for UO22+than for Th4+, probably due to the different linking degrees of hydrolysed species of these ions on the macromolecular compounds of the living cells through the chemical functional groups.