The influence of the low-intensity gamma-irradiation on the process of lipid peroxidation and the activities of the antioxidant glutathione-dependent system (catalase, glutathione-transferase) has been investigated in a number of Cladosporium cladosporioides (Fres.) de Vries strains. The dark-pigmented strains isolated from the habitats with different degree of radionuclide contamination, and the nonpigmented alb-mutant of the same species have been used in our work. The studied properties have been analyzed with the respect of the radiotropism property and of the presence of melanin pigment in the cell wall of these strains. The lipid perioxidation level under the effect of the low-intensity gamma-irradiation was greatly increased in Cladosporium cladosporioides 396 strain only. This strain was isolated from the radiation-pure soil. Catalase activity in a number of the studies strains correlated neither with their pigmentation, nor with the property of positive radiotropism. The correlation between the strain pigmentation and activity of glutathione transferase has been found.