Background  Despite decades of evidence from observational studies, the use of hormone therapy for the prevention of cardiovascular disease (CVD) among postmenopausal women is controversial. The recent completion of several randomised clinical trials examining the effects of hormone therapy on CVD presents an opportunity to provide a more precise estimate of the cardiovascular risks of hormone therapy.

Objective  To summarise the effects of hormone therapy on CVD in postmenopausal women.

Search strategy  MEDLINE, EMBASE, the Cochrane Library, DARE and CENTRAL were searched for clinical trials reporting mortality and/or CVD outcomes in association with hormone therapy. Bibliographies and editorials were also reviewed. All studies were reviewed and rated for quality independently by two reviewers.

Selection criteria  High quality, randomised placebo-controlled clinical trials of hormone therapy (duration greater than one year) in non-hospitalised postmenopausal women were included.

Data collection and analysis  Summary relative risks were estimated for all-cause mortality, coronary heart disease (CHD) mortality, non-fatal acute myocardial infarction (AMI) and all stroke.

Main results  Seven randomised clinical trials met the inclusion criteria. The use of hormone therapy had no significant effect on all-cause mortality, non-fatal AMI or CHD mortality, with relative risks of 1.02 [95% confidence interval (CI) 0.93–1.13], 1.00 (0.88–1.14) and 0.99 (0.82–1.21), respectively. For all stroke, the summary relative risk was 1.29 (1.13–1.48).

Author's conclusions  This systematic review, incorporating the latest available trial data, shows that hormone therapy does not significantly change the risk of all-cause morality, CHD death or non-fatal AMI but increases the risk of stroke in postmenopausal women.