The structure and function of members of the fibroblast growth factor (FGF) gene family and their receptors are reviewed. All the member of this gene family bind heparin, and therefore, are also called the as heparin-binding growth factor (HBGF). In this review, the structural features of FGF/HBGF are summarized first, and general features of the structure and function of their receptors are then described briefly. After biological effects of FGF/HBGF on adult-type tissues and cultured cells are reviewed, effects of FGF on the mesodermal induction in amphibian (Xenopus laevis) embryonic system are reviewed in more detail. Emphasis is given on the experiments with Xenopus animal cap assay system and also on the injection into Xenopus fertilized eggs of mRNA of dominant defect mutant of FGF receptor, which leads to the formation of embryos with abnormal axial mesoderm.