The aim of this study was to evalute the effect of multivitamin-mineral supplementation during pregnancy on plasma levels of antioxidants, erythrocyte antioxidant enzyme activities, and lipid peroxidation. A controlled, semi-randomized, prospective trial was performed by comparing the supplement group, which received multivitamin-mineral tables once daily for 10 weeks, with the control group. Plasma levels of $eta$-carotene, tocopherol, coenzyme Q10, ascorbate, folate, zinc, and selenium and malondialdehyde (MDA), as well as the activities of superocxide dismutase(SOD) and glutathione peroxidase(GSH-Px) in erythrocytes were measured initially (20 wk gestation) and at the end of the intervention (34 wk gestation). In the control group, plasma ascorbate and selenium levels decreased and tocopherol levels increased. In the supplement group, a significant increase in plasma $eta$-carotene(46%), conenzyme Q10 (42%), and zinc (24%) was observed after 10 weeks of supplementation. No changes were observed in the plasma levels of MDA, and erythrocyte GSH-Px activity, while SOD activity increased in both control group and the supplement group during the intervention. These data suggest that multivitamin-mineral supplementation during pregnancy produced moderate increases in plasma $eta$-carotens, coenzyme Q10, and zinc concentrations but the enhancement of those plasma antioxidants had on direct on the plasma level of MDA, erythrocytes SOD or GSH-Px activities.