Red blood cell glutathione and the enzymes responsible for its synthesis in erythrocytes were measured in mothers and their offspring at time of delivery. γ-Glutamyl cysteine (GC) synthetase was the same in the two groups (neonates 0.313 and mothers 0.330 μmol GC formed/g Hb/min). The GSH synthetase was lower in umbilical cord blood than in maternal blood (cord blood 0.169 and maternal 0.214 μmol GSH formed/g Hb/min), even though the reduced GSH was greater in the former group than in the latter (cord blood 2.83 and maternal 2.32 mg GSH/g Hb). There was no relationship between glutathione stability and glutathione synthetase levels.