An important development in the treatment of cancer is the recognition that the tumour's microenvironment, notably its vasculature, may be an attractive target for therapy. In the eighties of the last century, the concept of angiogenesis (the formation of new blood vessels from existing vasculature) was developed. Angiogenesis is the driving force behind tumour growth and metastasis. Recent angiogenesis research has elucidated the role of growth factors (vascular endothelial growth factor (VEGF), epidermal growth factor), metalloproteinases and endogenous proteins such as angiostatin and endostatin. This new knowledge has led to the rapid development of several angiogenesis inhibiting strategies. Although these new strategies showed very promising results in preclinical animal studies, early clinical studies with individual angiogenesis inhibitors have shown no antitumour effect so far. However, in recent studies blocking VEGF in addition to conventional chemotherapy has led to an increase in disease-free survival time and in response rate to chemotherapy. Angiogenesis research has contributed to the knowledge of the biology of cancer, the design of modified clinical studies and the development of surrogate markers that can be used as pharmacodynamic end points in future studies.