The efficacy of fulvestrant (Faslodex), a novel oestrogen receptor (ER) antagonist that downregulates the ER and has no known agonist effects, was compared with the aromatase inhibitor anastrozole (Arimidex) for the second-line treatment of advanced breast cancer in postmenopausal women with visceral and non-visceral metastases. Assessment was by means of a retrospective subgroup analysis of combined data from two randomised, phase III trials. Objective response (OR) rates were similar in patients treated with fulvestrant and anastrozole, respectively (21.9% versus 19.3%-patients with no visceral metastases; 15.7% versus 13.2%-all of the patients with visceral metastases; 18.8% versus 14.0%-patients with visceral metastases only). The proportion of patients with clinical benefit (CB) was also similar between treatments and between subgroups with and without visceral disease. Fulvestrant is at least as effective as anastrozole, providing a valuable treatment option for advanced breast cancer in postmenopausal women with visceral metastases who have failed on prior endocrine therapy.