There is increasing use of luteinising hormone-releasing hormone (LHRH) agonists in the adjuvant treatment of breast cancer (J. Clin. Oncol. 19(2) (2001) 343). However, few mature studies are available and there is uncertainty regarding the optimal use of these agents. We performed a systematic review to address the role of LHRH agonists in the adjuvant treatment of pre-menopausal women with early breast cancer. As ovarian suppression is unlikely to benefit women with ER-negative tumours, the review is limited to women with ER-positive disease. The objectives of this review were to address the following issues; the role of LHRH agonists compared to tamoxifen (TAM), LHRH agonists in place of chemotherapy and LHRH agonists integrated into chemo-hormonal regimens. We identified 11 randomised trials. In three trials, adjuvant suppression of ovarian function using LHRH agonists, with or without TAM, had similar benefits at 5-6 years follow-up in terms of disease-free survival (DFS) and overall survival (OS) to adjuvant CMF chemotherapy (J. Clin. Oncol 20(24) (2002) 4628; J. Natl. Cancer Inst. 95(24) (2003) 1833; Anticancer Res. 22 (2002) 2325; In: San Antonio Breast Cancer Symposium, San Antonio, TX, 2003, Abstr 40). These findings suggest that ovarian suppression using LHRH agonists (+/-TAM) is a reasonable alternative to CMF chemotherapy in women with oestrogen receptor (ER) positive tumours. The role of chemotherapy in addition to LHRH agonists is not clearly defined and mature results of four trials are awaited (J. Clin. Oncol. 20(24) (2002) 4621; J. Clin. Oncol. 18(14) (2000) 2718; Proc. Am. Soc. Clin. Oncol. 2000, Abstr 279; Proc. Am. Soc. Clin. Oncol. 20 (2001) Abstr 104; Proc. Am. Soc. Clin. Oncol. 2001, Abstr. 1777). Data is also inadequate at the time of publication to inform decisions about the efficacy of LHRH agonists in comparison with TAM for the treatment of ER-positive early breast cancer (Proc. Am. Soc. Clin. Oncol. 21 (2001) Abstr. 103; Eur. J. Surg. Oncol. 28(5) (2002) 505; Proc. Am. Soc. Clin. Oncol. 22 (2003), Abstr. 15).