Many studies have analysed the relation between hormone replacement therapy use and breast cancer risk. We performed a synthesis of their results based on a meta-analysis published in 1997, on fifteen observational studies published afterwards, and on a recent randomised trial. The accumulated evidence shows a higher risk of breast cancer among HRT ever users compared to non users. The risk increases with treatment duration and disappears a few years after the end of the treatment. Furthermore, recent observational studies showed that this risk may be higher when progestational agents are added to estrogens than when estrogens are used alone. This may be important in terms of public health since combination therapy with estrogen and progestational agents have become the standard of care among women with an intact uterus and are now commonly used. The effects of the treatments used in France, that are not those widely studied until now, must be evaluated, ideally through a randomized trial.