BACKGROUND The purpose of this study was to identify determinants of coronary artery reactivity among premenopausal female monkeys. Estrogen replacement therapy in postmenopausal females modulates reactivity of atherosclerotic coronary arteries. However, no studies have evaluated the factors that modulate coronary artery reactivity among premenopausal females. RESULTS Twenty-five adult premenopausal female monkeys were fed an atherogenic diet for 32 months. During this time, monkeys were housed in small social groups and determined to be socially dominant (associated with normal ovarian function) or subordinate (associated with impaired ovarian function). After 32 months, coronary artery vasomotor responses to intracoronary acetylcholine, nitroglycerin, and serotonin were assessed by computer-assisted quantitative coronary angiography. Coronary arteries of dominant monkeys dilated (+9 +/- 2%), whereas those of subordinate monkeys constricted (-6 +/- 2%) in response to acetylcholine (P < .05). There was no effect of social status on vascular response to nitroglycerin or serotonin (P > .10). Vascular responses to acetylcholine were independent of social status effects on plasma lipids, blood pressure, and atherosclerosis extent. The correlation between acetylcholine responses and plasma estradiol concentration measured on the day of angiography was r = .7 (P = < .01). Furthermore, dilation occurred only if plasma estradiol concentrations were greater than 60 pg/mL. CONCLUSIONS Psychosocial factors and endogenous estrogen production are important modulators of acetylcholine-mediated dilation of atherosclerotic coronary arteries among premenopausal female monkeys.