Abnormal endometrial bleeding plagues millions of women each year all over the world.An animal model is essential for elucidating the mechanisms and exploring treatments/therapeutic methods of such an annoying disorder in women.Rhesus monkeys have been used as a wonderful model in this case.There are two ways currently to create such a model.The first one is also the traditional method,i.e.removing the sources of estrogen and progesterone surgically-ovariectomy.The second technique is novel,i.e.knocking out the genes coding proteins which enhance estrogen or progesterone synthesis,usually on their pathway,in ovaries or their receptors in the endometrium by site-directed knockout,for instance,CRISPR/Cas9.The resultant model is fantastic.Researchers may use this wonderful animal model(1)to imitatethe periodic fluctuations –the vivid growth and dramatic shedding of the endometrium,and menses etc.;(2)to investigate abnormal bleeding caused by a variety of reasons;(3)to find therapeutic methods by testing medicines or compounds which may bevaluable to women with the disorder,such as the used progestinagonistlevonorgestrel(LNG),and progesterone receptor antagonist mifprogeston(EU486),and any new ones.