Vascular endothelial growth factor (VEGF) is an endothelial cell specific mitogen with strong angiogenic activity. Expression of VEGF may therefore be an indicator for the angiogenic potential and biological aggressiveness of a tumor. Recently, measurement of the VEGF-protein in sera has become available. We report results of serum-VEGF in an unselected group of patients with cancer with special emphasis on a possible role of anemia.