As a member of peroxiredoxin (Prx) family, PrxIII has been demonstrated to play an important role in scavenging intracellular reactive oxygen species (ROS). Since PrxIII knockout mice exhibited oxidative stress in placentas resembling pathophysiologic changes in placentas of human pre-eclampsia, we measured blood pressure through the carotid artery and detected oxidative status by western blotting in pregnant mice. We did not notice hypertension in pregnant PrxIII knockout mice as compared with wild-type littermates, although endothelin-1 was overexpressed in PrxIII-deficient placentas. Our results indicate that PrxIII is not involved in pre-eclamptic development. Instead, PrxIII is an indispensable antioxidant in placentas where oxidative stress exists.