Bacillus endospores show different kinds of pigmentation. Red-pigmented spores of Bacillus atrophaeus DSM 675, dark-gray spores of B. atrophaeus(T) DSM 7264 and light-gray spores of B. subtilis DSM 5611 were used to study the protective role of the pigments in their resistance to defined ranges of environmental UV radiation. Spores of B. atrophaeus DSM 675 possessing a dark-red pigment were 10 times more resistant to UV-A radiation than those of the other two investigated strains, whereas the responses to the more energetic UV-B and UV-C radiation were identical in all three strains. The methanol fraction of the extracted pigment from the spores absorbs in the associated wavelength area. These results indicate that the carotene-like pigment of spores of B. atrophaeus DSM 675 affects the resistance of spores to environmental UV-A radiation.