A randomized, double-blinded, placebo-controlled trial of uninterrupted transdermal nitrate therapy in 140 peri- or postmenopausal women who have frequent hot flashes. Women will be randomly assigned to uninterrupted use of transdermal nitrate therapy (participant directed dose-escalation of 0.2 to 0.6 mg/hr) or identical-appearing placebo patches for 12 weeks.