Fibroblast growth factor (FGF)-10 is a novel member of the FGF family. Although FGF-10 mRNA was preferentially expressed in the lung, the mRNA was also expressed, although at low levels, in the brain. We examined the localization of FGF-10 mRNA along with FGF-7 mRNA in the rat brain by in situ hybridization. FGF-10 mRNA showed spatially restricted expression in some regions of the brain, including the hippocampus, thalamus, midbrain and brainstem, although FGF-7 mRNA was not expressed in any of the brain regions examined. FGF-10 mRNA was strongly expressed in several restricted nuclei, especially in motor nuclei, including the oculomotor nucleus, dorsal motor nucleus of vagus, motor trigeminal nucleus, facial nucleus and hypoglossal nucleus. This localization pattern was distinct from those of aFGF, bFGF FGF-5 and FGF-9 mRNAs reported previously. The cellular localization of FGF-10 mRNA showed that the mRNA in the brain was preferentially expressed in neurons but not in glial cells. The present findings indicate that FGF-10, an additional member of the FGF family expressed in the brain, has a distinct role in the brain.