Since the recognition of the importance of the vascular bed for growth and metastasis of solid tumours, many researchers have investigated the approach of attacking the tumour vascular bed instead of the tumour cells themselves in anti-cancer therapy. Such approaches have become possible with the increasing knowledge of the angiogenic process and the factors that regulate it. Especially the potent angiogenic factor VEGF has been the subject of extensive study in this regard. A number of studies showed that inactivation of this factor or its receptors led to a profound negative effect on the development of experimental tumours. However, despite the encouraging results obtained in animal studies, it remains to be established whether human tumours, which might be in a state of relative quiescence, are as sensitive to anti-VEGF treatment as the fast-growing tumours that are generally used in animal studies. If so, anti-VEGF treatment might certainly represent a powerful tool in anti-cancer therapy, either or not in combination with other blockers of angiogenesis.