Postmenopausal women have more severe endothelial dysfunction than premenopausal women. In the present study, we evaluated the possible beneficial effect of raloxifene administration, a selective estrogen receptor modulator, on endothelial regulation in postmenopausal women. In a double-blind, randomized vs. placebo trial, 60 healthy postmenopausal women were treated with raloxifene (60 mg/d) or placebo for 4 months to evaluate the effect of raloxifene treatment on endothelial function. Furthermore, in raloxifene-treated subjects (n = 30), the effect of raloxifene was also assessed during the intraarterial infusion of N(G)-monomethyl-L-arginine (4 micromol/min). Raloxifene administration vs. placebo was associated with a decrease in plasma low-density lipoprotein cholesterol (P < 0.01), triglyceride (P < 0.05), thiobarbituric acid-reactive substance (P < 0.01), vascular cell adhesion molecule-1 (P < 0.05), intercellular adhesion molecule-1 (P < 0.001), and E-selectin (P < 0.001) levels and with an increase in plasma Trolox equivalent antioxidant capacity (P < 0.001) levels. Indeed, raloxifene treatment was also associated with a significant improvement in endothelial-dependent vasodilatation assessed by brachial reactivity technique. Raloxifene administration had no impact on endothelial-independent vasodilatation. Furthermore, intraarterial infusion of N(G)-monomethyl-L-arginine inhibited the significant effect of raloxifene on endothelium-mediated brachial arterial diameter and flow. In conclusion, our results demonstrate that raloxifene administration is associated with a positive modulation of endothelial-dependent vasodilatation likely due to a reduction of risk factors for endothelial damage.