Metastatic breast cancer remains an essentially incurable disease and chemotherapy, despite producing frequent and clinically useful responses, has had a disappointing impact on survival. Several highly promising lines of clinical research with new agents, combinations and dosages may yet produce an improved outcome. Of the new drugs that have been studied, the taxoids, docetaxel and paclitaxel appear to be the most active agents yet discovered in this setting; navelbine is also active. Investigations of high-dose chemotherapy have produced the highest rates of complete response achieved in patients with this condition. The results of recent randomised trials confirm the high activity of this modality and also suggest a survival advantage compared with more traditionally dosed treatment. Active research into biological therapy is also under way and vaccines, antibodies and inhibitors of growth factors are all being evaluated.