Co-administration of antihypertensive drug therapy and hormonal replacement therapy (HRT) is frequent in postmenopausal women but it is not known whether HRT interacts with concomitant antihypertensive therapy. The present study was designed to investigate efficacy and safety of the ACE inhibitor moexipril in comparison to placebo in hypertensive, postmenopausal women on HRT. After a 4-week placebo run-in phase, 95 postmenopausal women (35-74 years of age) who had a sitting diastolic blood pressure (BP) of 95-114 mmHg and were treated with HRT were randomised to a 12-week treatment with moexipril 15 mg or placebo. Efficacy and safety were assessed by measuring changes in sitting BP and metabolic parameters associated with cardiovascular disease including triglycerides, total cholesterol, HDL, LDL, total cholesterol/HDL ratio and glucose. Adverse events were recorded continuously. After 12 weeks of treatment, moexipril 15 mg was significantly more effective in reducing sitting systolic and diastolic BP from baseline than placebo (-12.2/-9.9mm Hg vs -1.6/-4.3 mmHg, P < 0.001). Metabolic parameters were not affected by treatment with moexipril: mean levels of triglycerides, total cholesterol, HDL, LDL, total cholesterol/HDL ratio and glucose remained unchanged throughout the study. Fibrinogen, an independent cardiovascular risk factor, increased after placebo (+35.0 mg/dl) and decreased after treatment with moexipril (-33.6 mg/dl), the difference, however, was not statistically significant. Moexipril was well-tolerated by postmenopausal women using HRT. The most frequent adverse events included headache (21.3%), cough (12.8%) and rhinitis (10.6%) and there were no significant differences in the number and severity of adverse events between the moexipril and placebo groups. This study indicates that moexipril is effective and well tolerated in the treatment of hypertensive, postmenopausal women and can safely be co-administered to HRT.