Disinfectants are commonly used in households, hospitals, in drug manufacturing, in food processing. With the ever-increasing antibiotic-resistance of microorganisms, it is crucial to rationally apply disinfectants in suitable concentrations, with proper active substance, as not all substances affect various organisms in the same way. Among the microorganisms that are particularly difficult to kill, there are bacteria producing spores - forms that have different structure and sensitivity to disinfectants than the vegetative forms. The aim of the study has been to examine the influence of frequently used disinfectant compounds upon the spores of bacteria of the Bacillus genus: B. cereus, B. mycoides, and B. subtilis. In the study of disinfectants the findings showed that the disinfectants with the best results against spores are: peracetic acid, hydrogen peroxide in concentrations of 30% as well as 5%, and Lysoformin 3000. The least efficient in fighting spores proved to be Isopropanol and Promanum N. Differentiation has been found to exist in the reaction of specific species to the preparation Rafasept, as B. subtilis occurred to be very sensitive to that compound, whereas Rafasept turned out to be ineffective in the case of B. mycoides and B. cereus.