We isolated rat FGF-5 cDNA and its variant from the embryo. The FGF-5 cDNA encodes a protein of 266 amino acid residues. The variant cDNA encodes a protein of 121 amino acid residues, the N-terminal 117-amino acid sequence of which is identical to that of FGF-5. Thus the variant cDNA encodes a novel truncated form of FGF-5. The rat FGF-5 gene consists of three exons (exons 1-3). The variant cDNA lacks the nucleotide sequence of exon 2, indicating that the variant mRNA is generated by alternative splicing. The variant mRNA as well as the FGF-5 mRNA was detected in the embryo and adult brain. This is the first description of the mRNA for a truncated form of FGF within the FGF family.