Hepatocyte growth factor (HGF), which is also known as the scatter factor, is a broad-spectrum and multifunctional cytokine, mediates epithelial-mesenchyme interaction, and is shown to be involved in the development and regeneration of various tissues, including tooth. Here, we report that HGF was present in adult human dental pulps, and its levels increased during acute inflammation of the tissue. Levels of HGF mRNA in dental pulps also increased with inflammation, as determined by reverse-transcription/polymerase chain-reaction. The production of HGF in fibroblasts from dental pulps in culture was dose-dependently stimulated by inflammatory cytokines such as interleukin (IL)-1 alpha and tumor necrosis factor (TNF)-alpha, and by prostaglandin (PG) E-2, as determined by an enzyme-linked immunosorbent assay. We also showed that indomethacin did not affect the increase in HGF production by the cells with IL-1 alpha, TNF-alpha, and PGE(2). The levels of HGF mRNA in the cells were simultaneously increased by these stimulants, as determined by Northern blotting. Since the production of PGs is known to increase at the beginning of inflammation, PGE(2) may be involved in the regeneration of dental pulps by the induction of HGF expression after inflammation.