Seven bovine follistatin (FS) cDNA clones were isolated from a bovine ovarian follicle cDNA library. The predicted amino acid sequences revealed that six of the cDNA clones represented an FS precursor of 344 amino acids which corresponded to a mature FS of 315 amino acids (FS 315), with one cDNA clone containing the entire coding sequence including 180 nucleotides of 5′ untranslated sequence. The predicted amino acid sequence of the seventh cDNA clone, which differed in the 3′ coding sequence, represented a precursor protein of 317 amino acids, corresponding to a mature FS of 288 amino acids (FS 288). This clone encoded an identical amino acid sequence to the other six cDNA clones except that the C terminal of FS 315 was truncated by 27 amino acids. The sequence of bovine FS was found to contain 36 cysteine residues and 2 potential N-linked glycosylation sites. The predicted amino acid sequence of bovine FS has overall sequence homologies of 98% with ovine FS and 97% with human FS.