In a study to assess the antioxidant activity of proanthocyanidin (Pro), 90 adult female Balb/c mice weighing 35-40 g were evenly divided into six groups. The experimental groups were administered Pro by gavage (25-50 mg/kg bw/day) (Pro-25, Pro-50) and sodium fluoride in drinking water (250 mg F ion/L) either alone (F in DW) or consecutively (F+Pro-25 and F+Pro-50) in certain periods of the trial. Blood samples were collected in heparinised tubes on days 0, 7, 8,10,12, and 15. Compared to the control group, plasma malondialdehyde (MDA) levels increased significantly at day 7 by 54.25%, 57.76%, and 53.71% and at day 8 by 47.33%, 54.41%, and 48.40% for the F in DW, F+Pro-25, and F+Pro-50 groups, respectively. On the other hand, erythrocyte superoxide dismutase (SOD) activities decreased significantly at day 7 by 48.15%, 46.30%, and 48.15% and at day 8 by 43.40%, 37.74%, and 37.74% for the same groups. Like MDA levels, erythrocyte catalase (CAT) activities increased significantly at day 8 by 59.50%, 56.20%, and 58.68%, at day 10 by 42.52%, 38.58%, and 38.58%, and at day 12 by 47.50%, 34.17%, and 27.50% for the same groups. On day 10, the plasma MDA levels in the F+Pro-25, and F+Pro-50 groups were decreased by 12.48% and 15.86% compared to the F in DW group and were close to that of the control group. Similarly, on day 15, the plasma MDA in the high dosage F+Pro-50 group showed a 9.32% decrease compared to the F in DW group and was close to that of the control level. In conclusion, exposure of mice to 250 mg F/L in their drinking water for the indicated periods of time was found to cause oxidative stress that was reduced by administration of Pro.