Angiogenesis, the formation of new capillaries from existing blood vessels, is necessary for embryonic growth and development. It is also seen later during the female cycle and wound healing, but is virtually absent otherwise in the healthy adult organism. Angiogenesis is again observed under pathological conditions, like for example in solid pediatric malignancies. Once grown to a diameter of several millimeters, the latter depend on angiogenesis in order to further grow and to metastasize. Recent experimental and clinical evidence suggests 1) that the extent of tumor angiogenesis could serve to predict clinical outcome and 2) that the inhibition of angiogenesis could be a means to improve the conventional therapy of solid pediatric malignancies.