Abstract: Objective To observe the permeability of recombinant human erythropoietin through placenta barrier and fetal blood-brain barrier after transient uteroplacental ischemia. Methods Rats on days 19 of pregnancy were divided into rhEPO treated group, ischemia-reperfusion group and sham-operated group. Fetal ischemia in rhEPO treated group and ischemia-reperfusion group was induced by bilateral occlusion of the utero-ovarian artery for 20 minutes. Different dosage of ¹²⁵I-rhEPO (2500 U/kg,5000 U/kg,7500 U/kg) was injected into the rats through caudal veins 30 min before injury in rhEPO treated group and sham-operated group. Saline was administered intravenously 30 min before the induction of hypoxic-ischemic injury in ischemia-reperfusion group. The amniotic fluid, placenta and fetal organs including brain, liver, heart, lung and kidney were collected to measure the radioactivity at 24h after injury. Results ¹²⁵I-rhEPO was detected in amniotic fluid, placenta and fetal organs. The radioactivity of ¹²⁵I-rhEPO in these tissues increased gradually with the increased dose injected in rhEPO treated group and sham-operated group. There were significant differences in the radioactivity of ¹²⁵I-rhEPO between rhEPO treated group and sham-operated group (P<0.05). Conclusion The permeability of rhEPO through placental barrier and blood-brain barrier increased under the condition of fetal ischemia and hypoxia.