Reptilia is the only vertebrate class in which cDNA for the gonadotropin β subunit precursor molecule has not been cloned. We have isolated the full-length cDNA clone encoding the LH β subunit precursor molecule and a partial cDNA clone encoding the FSH β subunit precursor molecule from a pituitary cDNA library of Reeves’s turtle. We further clarified the nucleotide sequence of the remaining part of the turtle FSH β cDNA and that of full-length cDNA encoding the LH β subunit precursor molecule of the Japanese grass lizard, by means of the 5 ′ rapid amplification of cDNA end (RACE) and 3 ′ RACE. The nucleotide sequence of the turtle FSH β cDNA we determined was 584 bp long and contained the coding sequence, 5 ′ untranslated region (UTR) and 3 ′ UTR of 396, 34, and 154 bp, respectively. The nucleotide sequence of the turtle LH β we isolated was 498 bp long and contained the coding sequence, 5 ′ UTR and 3 ′ UTR of 420, 7, and 71 bp, respectively. The nucleotide sequence of the lizard LH β we determined was 537 bp long and contained the coding sequence, 5 ′ UTR and 3 ′ UTR of 441, 35, and 61 bp, respectively. Amino acid sequences deduced from coding regions of the turtle FSH β, LH β and the lizard LH β were 131, 139, and 146 residues, respectively. Referring to the amino acid sequences of the bullfrog FSH and LH β subunit molecules determined chemically, we deduced the amino acid sequences of mature peptide. Amino acid sequences of mature peptides of the turtle FSH, turtle LH, and the lizard LH were 111, 112, and 112 residues, respectively. Amino acid sequences of the mature peptides were compared with those of other vertebrates. The amino acid sequence of the turtle FSH β subunit molecule was 84.7–85.6, 67.8–71.4, and 61.3–62.2% identical to the FSH sequence of birds, mammals, and amphibians, respectively. The amino acid sequence of the turtle LH β subunit molecule was 51.6–54.6, 36.2–48.7, and 56.3–57.5% identical to the LH sequence of birds, mammals, and amphibians, respectively. The amino acid sequence of the lizard LH β subunit molecule was 39.1–47.1, 32.9–43.0, and 46.0–47.3% identical to the LH sequence of birds, mammals, and amphibians, respectively. These identity values suggest that the turtle or reptilian FSH β subunit molecule is more closely related to avian and mammalian FSH β subunit molecules than to amphibian FSH β subunit molecules but reptilian LH β subunit molecules are more closely related to amphibian LH β subunit molecules than to avian and mammalian LH β subunit molecules. This discrepancy in the molecular similarity relationship found in the reptilian FSH and LH β subunit molecules can be interpreted by assuming that evolution speed was not the same among hormone species and also among vertebrate groups.