The formation of new vessels (aka neo-angiogenesis) is critical for tumoral progression. Although anti-angiogenic therapies targeting the vascular endothelial growth factor (VEGF) pathway are employed since less than ten years in human patients, they are now a key player in the treatment of advanced stage malignant tumors. An endothelial syndrome, characterized by hypertension and glomerular proteinuria, complicates this treatment in roughly 25% of patients. From a pathophysiological perspective, this may be considered as a preeclampsia-like syndrome. While the most severe forms require the interruption of the regimen, this syndrome is usually mild or moderate, and should be treated by the addition of an anti-hypertensive drug.