Various members of the fibroblast growth factor (FGF) family of proteins have been shown to protect against acute and late radiation damage of normal tissues. Protection of the small bowel, for example, occurs via both increased proliferation and reduced apoptosis. Other beneficial effects of FGFs include promotion of bone growth, pneumonitis prevention, and apoptosis suppression of endothelium in vivo and in vitro after irradiation. This protection against radiation requires only low and infrequent doses of FGFs. Two newly identified members of the FGF family, FGF7 and FGF10, have effects similar to many of the other FGF family proteins, but with more specificity for normal epithelial structures. For this reason, they have also been named keratinocyte growth factors one and two (KGF1 and KGF2, respectively). We therefore examined the potential utility of KGFs for radioprotection of the bone marrow and small bowel and examined safety issues concerning their adverse effects on KHT sarcoma. The results suggest that KGFs could be safely used to prevent radiation toxicity of the abdomen or pelvis and may in fact improve tumor response to radiation.