Fibroblast growth factors (FGFs) are important regulators of cell migration, proliferation and differentiation, e.g., during embryogenesis and wound healing, and under several pathological conditions including tumor growth and tumor angiogenesis. Since heparin-binding FGFs are tightly bound to heparansulfate proteoglycans, and therefore, trapped in the extracellular matrix, their release through the action of an FGF-binding protein (FGF-BP) is one of the critical steps in FGF bioactivation. FGF-BP expression is highly tissue specific and strictly regulated through different promoter elements. Besides its role in embryogenesis and wound healing, FGF-BP is upregulated in several tumors and it is associated especially with early stages of tumor formation, where angiogenesis plays a critical role. Concomitantly, in several mouse tumor models, targeting of FGF-BP by ribozymes or RNA interference (RNAi) abolishes or reduces tumor growth and tumor angiogenesis. This indicates that FGF-BP can be rate-limiting for tumor growth and serves as an angiogenic switch molecule, and that it represents an increasingly promising target molecule in anti-tumor therapy.