Objective In order to improve the preparation efficiency of mouse dormant embryos,the normal superovulation combined with anti-PMSG serum(A-PMSG) was applied to collect the dormant ones.Methods According to the different doses of A-PMSG injected into the mouse after injection of PMSG,the mice were divided into five groups: 1) injecting A-PMSG before mating,2) injecting A-PMSG after finding a vaginal plug,3) injecting A-PMSG after ovariectomy in the morning of day 4(day1= vaginal plug),4) superovulating without A-PMSG,and 5) the control one.Results The average number of recovered embryos(9.4) of the group injected with the A-PMSG after finding a vaginal plug,is significantly higher than the other groups(P<0.01).Conclusion Superovulation combined with anti-PMSG serum can improve the collecting efficiency of murine dormant embryos.