Abstract: Objective To investigate the clinical efficacy of estrogen in management of postpartum hemorrhage due to uterine atony. Methods Totalling 112 puerperants with postpartum hemorrhage due to uterine atony were randomly assigned into 2 groups and received routine managements for uterine atony such as uterine massage and uterotonics administration. The puerperants in one group (n=52) was treated with 4 mg estradiol benzoate injected intramuscularly, and the amount of blood loss 2 h after delivery and between 2 and 24 h after delivery was recorded. Results There were significant differences in vaginal blood loss at 2 h after delivery between the 2 groups (P<0.05). The puerperants with estrodiol benzoate treatment had blood loss of 589.6±226.4 ml at 2 h and 110.8±76.2 ml within 2-24 h after delivery, which were both less than those in the control group (864.5±359.5 ml and 161.5±98.3 ml, respectively). Postpartum hysterectomy was performed in 3 cases of the control group while none in estradiol benzoate-treated group. In the mothers and neonates, no major adverse effects were observed. Conclusion Estrogen shows cooperative efficacy with uterotonics in stimulating uterine contraction for managements of postpartum hemorrhage due to uterine atony, and can be of value in clinical application.