The human feto-placental unit being in the environment of the materno-fetal circulation is very much susceptible to the danger of reactive oxygen species-induced oxidative damage. The present study reports the status of various antioxidants in the feto-placental system at birth. The activities of superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase as well as concentrations of non-enzymic antioxidants viz, ascorbic acid, α-tocopherol, bilirubin and glutathione have been determined in term placental brush border membrane (BBM) and umbilical cord (UC) blood. The extent of lipid peroxidation in developing and term BBM and UC blood has been studied by estimation of malondialdehyde and conjugated dienes, both being the end products of lipid peroxidation. The results indicate the presence of a protective mechanism against oxygen toxicity in the feto-placental system at the time of parturition. Copyright (C) 1999.