This mini review highlights the role of vascular stabilization which is apparently mediated by factors belonging to both the pro- and anti-angiogenic group. Knowingly angiopoietin-1 has pro-angiogenic properties while endostatin acts anti-angiogenic. But both factors suppress tumor growth in experimental tumor models. The crossing points of mechanisms of their action are the parameters vascular stabilization and vascular permeability, which are of high importance not only for tumor vascularization, but also for tissue vascularization in general. Both angiopoietin-1 and endostatin reduce the vascular permeability, but promote vascular stabilization. Vascular stabilization is significantly increased under experimental treatment of tumors with angiogenesis inhibitors such as endostatin. It inhibits tumor growth and probably tumor metastasis. The understanding of temporal and spatial sequences of vascular stabilization is an important challenge for scientists working on tumor vascularization and anti-angiogenic tumor therapy.