This paper outlines the development of fulvestrant, the first in a new class of antioestrogen agents with no agonist effects, to be used for the treatment of hormone receptor-positive advanced breast cancer in postmenopausal women. The role of the oestrogen receptor in breast cancer growth and development and the evolution of pharmacological strategies to manipulate it are also discussed. Preclinical and clinical evidence for the efficacy of fulvestrant are also reviewed, along with the tolerability profile of this agent in relation to other endocrine therapies. Further research will define the role of this exciting new agent in the endocrine treatment of breast cancer.