Twenty-two pre-menopausal evaluable patients with advanced breast cancer (median age 39 years; ER positive 19, unknown three; prior adjuvant chemotherapy 16) were treated with the LHRH agonist goserelin depot (Zoladex*). Serum levels of 17 β-estradiol and progesterone were suppressed by goserelin within 3–4 weeks of therapy, while serum leuteinizing hormone and follicle stimulating hormone titers remained in the low level of the normal range. Complete or partial response was documented in seven of 22 cases (32%) and occurred in all major sites of disease. Tumor response was documented in women regularly menstruating at the start of therapy. Median time to disease progression was 23 weeks; median duration of response was 64 weeks; overall survival was 141 weeks. Zoladex was well tolerated: only hot flushes in 82% and reversible cutaneous plgmentation in the site of injection in 45% of the patients were observed. In our experience the activity of Zoladex was comparable to that of oophorectomy, without the psychological trauma and the morbidity related to surgical castration.