The preoperative use of systemic therapy for primary breast cancer has the potential to downstage tumours. This would render suitable for breast conservation some tumours that were unsuitable at initial presentation, or would convert some inoperable locally advanced breast cancers into tumours that are operable. No survival benefit has been demonstrated for neoadjuvant chemotherapy compared with the same therapy given in an adjuvant setting. Preoperative endocrine therapy, in contrast to neoadjuvant chemotherapy, has fewer side effects and has the potential additional advantage that it can be continued throughout the perioperative period. Current data have shown that, in patients with an oestrogen receptor (ER)-positive tumour, a response approaching 70% could be reached in approximately 3 months using traditional endocrine manipulation such as tamoxifen. Randomised clinical trials are warranted to demonstrate the superiority of preoperative endocrine therapy over conventional adjuvant endocrine therapy, to define the optimum duration of therapy, and to identify the best endocrine agents. Both clinical and laboratory studies are also required to identify factors (in addition to ER) that would precisely predict the response and hence to select appropriate patients and to improve existing methods of monitoring response.