Keratinocyte growth factor (KGF) is a member of the fibroblast growth factor family whose specificity for epithelial tissues is a consequence of the restricted expression of its receptor, KGF receptor (also known as FGFR2IIIb), on epithelial cells. KGF is typically expressed in stromal or mesenchymal cells adjacent to epithelia and is thought to be an endogenous paracrine regulator of epithelial cell growth, differentiation, and repair. Administration of recombinant human KGF (rHuKGF) has growth, differentiating, and cytoprotective effects on epithelium in animals and humans, and may be a potential therapeutic agent for a variety of conditions involving epithelial injury and/or inflammation. Clinical studies in cancer patients provide evidence that rHuKGF is therapeutically effective in ameliorating chemoradiotherapy-induced oral epithelial injury.