The aim of the wok is to assess the efficiency of hormone-regulating synchronization of ovulation in female mice, to increase the number of simultaneously fertilized individuals and obtain their offspring in the planned time frame.Materials and methods. The study was carried out on 180 female mice of three lines – CBA/lac, C57BL/6, BALB/c (n = 60), divided into three subgroups: intact (mating without confirmation of the estrous phase) (n = 20), cytological examination of vaginal secretions before mating with the determination of the estrous phase (n = 20), hormone-regulating synchronization of the estrous cycle with the introduction of progesterone (4.5 mg/100 g) on the 1st and prostaglandin F2α (0.083 mg/100 g) on the 7th day, once from the beginning of the experiment followed by immediate mating (n = 20). The planned date of delivery was considered the 22nd day from the moment of mating. The ovulation synchronization index (OSI) was assessed on the 14th day after mating.Results. On the 14th day from the beginning of the experiment, the ovulation synchronization index in the intact groups of the CBA/lac, C57BL/6, BALB / c lines, was 25%, 25%, 40%, respectively. On the 14th day, the number of pregnant individuals admitted to mating after the established estrus by the method of cytological assessment of vaginal secretions according to OSI, was 65%, 60%, 75%, respectively. In the experimental groups, OSI was 80%, 75%, 100%, respectively. On the 22nd day, the number of delivered females of CBA/lac, C57BL/6, BALB/c lines in the intact group, was 3, 1, 3 individuals; in the control group – 10, 6, 9, and in the experimental group – 16, 15, 17, which is significantly higher than in the control and intact groups (p˂0.05).Conclusion. Hormone-regulating synchronization of ovulation in female mice significantly increases the number of delivered individuals on the 22nd day, relative to those synchronized by estrus by 53%, and to intact groups by 85.5%. It has been revealed that an additional effect of hormonal synchronization of ovulation is an increase in the number of offspring by 120% in comparison with the control groups and by 390% in comparison with the intact groups. This method of timing planning of the offspring birth of the experimental animals reduces the time spent on preclinical studies of drugs for the following types of assessment of toxic effects: reproductive toxicity, embryotoxicity, teratogenicity, effects on fertility.