The purpose of scientific research was to study the effect of the developed biologically active drug «Stimulin» on the level of superovulatory treatment with PMSG «Folligon» and the quantitative yield of the number of transferable embryos. The experiments were conducted on donor cows of the Ukrainian Black-and-White breed. Experimental donor cows were intramuscular administration injected for 8, 9, 10, 11 days of the oestrous cycle by drug «Stimulin» in a single dose 20 ml. Control animals in these days were similarly administered 20 ml of physiological saline solution. It was established that, when gonadotropin PMSG “Folligon” of a polyovulatory reaction in donor cows, receiving an intramuscular administration of the drug "Stimulin" dose of 20 ml from day 8 to 11 after estrus , promotes a positive trend until its level and the number of embryos suitable for transplantation increase (by 28,5 %), and also reduces neovulated follicles by 27,5%. With induction of gonadotrophin PMSG“Folligon” by superovulation in donor cows, receiving an intramuscular administration from day 8 to day 11 after estrus of the drug "Stimulin", contributes to the tendency to increase the level of superovulation and the number of transferable embryos and reduces the number of non-ovulated follicles.