Frequency of cytogenetic disturbances was estimated in mitotically dividing bone marrow cells of CBA strain female mice after 24-h long action of pheromone 2,5-dimethylpyrazine (2,5-DMP). The stage of estrus cycle of each animal was taken into acount at the moment of the end of the pheromone action. The analysis was performed using the anatelophase method that allows evaluating frequencies of various types of disturbances-bridges, fragments, delayed chromosomes. The spontaneous level of the mitotic disturbances revealed by the anatelophase method in animals of the control group amounts to 5.4%. Action of pheromone 2,5-dimethylpyrazine induced the mitosis disturbances detected in the dividing bone marrow cells at the anaphase-telophase stage in the females at the di-+ postestrus stage. The corresponding frequency of disturbances after the pheromone action was equal to 9.2%. In the female in estrus, the mitotic disturbance level amounted 6.7%, which not differed statistically significantly from control. It is suggested that differences in female mouse hormonal state at different estrus cycle stages affect sensitivity to olfactory signals. Mechanisms of the revealed effect and significance of the differences in sensitivity to pheromone for reproductive processes are discussed.