The fibroblast growth factor receptors (FGFRs, RTK class V, FGF receptor family) include the four highly conserved transmembrane receptor tyrosine kinases FGFR1, FGFR2, FGFR3, and FGFR4. One additional receptor, FGFR5 (FGFRL-1), is devoid of kinase activity but able to bind FGFs and may act as a negative regulator of signaling. The FGF signaling pathway plays a critical role in many physiological processes during embryonal development and maintenance of adult organ systems, including angiogenesis and wound repair, cell proliferation, migration, differentiation, and cell survival. Aberrations in this signaling pathway can give rise to tumor progression and growth of multiple cancer types. In addition, it may serve as a mechanism of resistance to antivascular endothelial growth factor targeted therapy. As such this pathway has emerged as a relevant therapeutic target, and several agents that can inhibit or modulate its signaling are in various stages of development.