It is well documented that there are gender differences in the incidence and patterns of cardiovascular disease; males have a higher incidence of cardiovascular disease than premenopausal women. We have therefore investigated whether the sex hormones, estradiol and testosterone, could directly influence the secretion of vascular peptides from human aortic endothelial cells (HAEC). Previously we have shown that testosterone can increase the number of HAECs that secrete adrenomedullin. In this study we investigated sex hormone regulation of endothelin-1 in HAEC. Several studies have observed a reduction in endothelin-1 secretion from endothelial cells in the presence of estradiol, the effect being more marked for stimulated cells. Studies on the actions of testosterone are much fewer and inconclusive. In this study we observed that estradiol did not change the number of cells secreting endothelin-1 during 4 h incubation under basal conditions but decreased the number of secreting cells stimulated with angiotensin-II. Testosterone induced an increase in the number of cells secreting endothelin-1 (p = 0.03). Complementary incubations revealed that testosterone up-regulated endothelin-1 mRNA at 1–3 h (p < 0.05). These results, together with our previous observations, indicate that angiotensin-II, testosterone and estradiol have parallel effects on the production of endothelin-1 as on adrenomedullin in HAEC. We conclude that there is potential for coordinated modulation by sex steroids and angiotensin-II of vasoactive peptide production in human endothelial cells.