Progress in the treatment of breast cancer developed along multiple directions of research during the last decade. The concept of dose-intensity was addressed through retrospective analyses and prospective randomized trials. It was confirmed that dose-intensity correlates with higher response rates, but the effect of dose-intensive treatments on survival still needs to be established. Several new cytotoxic drugs have appeared during the last several years. Taxol, navelbine, and anthrapyrazole CI-941 have been found to have major efficacy against breast cancer, with response rates exceeding 50%. Amonafide, lonidamine, and elliptinium analogs were also shown to be effective, although to a lesser degree. Antiestrogen analogs, new aromatase inhibitors, and LHRH analogs are recent developments that are changing the face of hormonal therapy. Monoclonal antibodies are being developed and evaluated for tumor imaging applications and as vehicles for specific antitumor agents (cytotoxics, radioisotopes, and toxins). Expanding knowledge about the basic biology of breast cancer has led to the identification of growth factors and their receptors, which may be exploited for therapeutic purposes in the not too distant future.