Objectives: To investigate the antioxidant status of normotensive and hypertensive Nigerians and the effect of antioxidant vitamin supplementation on sustained blood pressures (systolic blood pressure ≥160mm Hg and diastolic blood pressure ≥100mm Hg) in hypertensive subjects. Methods: A total of 130 subjects aged 25–68 years were recruited for the study. Of the hypertensive subjects investigated, 30 were newly diagnosed and were not on any antihypertensive drug, but had systolic blood pressure ≥160mm Hg and diastolic blood pressure ≥100mm Hg, and 50 were already on drug therapy. Fifty were Nigerian normotensive controls with blood pressure ≤120/90mm Hg. Results: Measurement of catalase and superoxide dismutase activities and plasma concentrations of ascorbic acid (vitamin C) and tocopherol (vitamin E) as an assessment of total antioxidant status indicated that hypertensive subjects had a significantly lower antioxidant status than normotensive subjects (p < 0.05). Antioxidant vitamin supplementation for 2 weeks reduced systolic/diastolic blood pressures of the newly diagnosed hypertensive subjects from 171/104 to 164/95mm Hg, while the hypertensive subjects already on antihypertensive drugs had their blood pressures reduced significantly to 136/85mm Hg. Conclusions: The beneficial effects of blood pressure lowering in hypertensive subjects by antihypertensive drug therapy is improved and is further enhanced when their antioxidant status is adequately high.