We measured flow-mediated dilation (FMD) by high-resolution brachial ultrasound in 61 women who participated in the Women's Angiographic Vitamin and Estrogen (WAVE) trial, a randomized controlled trial. There were no significant differences in the baseline demographics of women receiving hormone therapy (0.625 mg/day of conjugated equine estrogen plus 2.5mg of medroxyprogesterone acetate for women who had not had a hysterectomy) or placebo; or vitamins (400 IU of Vitamin E and 500 mg of Vitamin C twice daily) or placebo. Baseline FMD was impaired in all subjects (3.3+/-7.6%). Neither hormone therapy (4.1+/-5.2% at baseline, 4.2+/-5.0% at 3 months, and 4.1+/-6.5% at 34 months) nor antioxidant vitamins (3.0+/-8.3% at baseline; 3.5+/-4.6% at 3 months; 3.1+/-7.6% at 34 months) improved FMD (all p-values=NS). Endothelium-independent vasodilation, induced by nitroglycerin (NTG) was similar at baseline and was not affected by either therapy. In univariate and multivariate analysis, neither hormone therapy nor antioxidant vitamins were associated with FMD. Women with established coronary artery disease have impaired flow-mediated vasodilation of the brachial artery that does not improve after 3 months or up to 34 months of treatment with postmenopausal hormone therapy or antioxidant vitamins.