The evolutionarily conservative 2,5-dimethylpyrazine chemosignal, a pheromone released by female mice, has been shown to increase frequency of mitotic disturbances in bone marrow cells assessed by using metaphase and ana-telophase analyses. The substitution of methyl radical in the molecule of pheromone by carboxyl reveals specificity of the effect of the latter derivative: the frequency of disturbances revealed by the ana-telophase analysis alone increases, whereas no induction of disturbance is detected by the metaphase analysis. An increase of the anomalies induced by both compounds has been shown in a sperm head test. Possible mechanisms underlying specific action of the tested substances on stability of the genetic apparatus of bone marrow dividing cells in the house mouse are discussed.