While the value of hormone replacement therapy appears now to be accepted, it is above all a prophylactic technique requiring evaluation of its benefit/risk ratio. The possible increased risk of breast cancer linked to this type of treatment remains a preoccupation which probably limits its more widespread use. The natural history of this cancer and inherent biases in the various types of study are such that analysis of the literature is often difficult and any definite conclusion is prevented. Certain trends nevertheless appear to emerge from the principal studies. While there is indeed an increased risk of onset of breast cancer, it is slight, other than with the use of high doses of estrogens for prolonged periods in women with a family history of breast cancer. Decreased overall mortality rate in women on replacement therapy and the improvement in their comfort tend to suggest that it is now legitimate to offer such treatment, provided its contra-indications are strictly observed and regular monitoring is ensured.