We prepared the polyclonal antibody anti-$20{alpha}$-hydroxysteroid dehydrogenase (anti-$20{alpha}$-HSD) against the recombinant full-length protein bovine $20{alpha}$-HSD in Escherichia coli. The specificity of anti-$20{alpha}$-HSD was demonstrated using Chinese hamster ovary (CHO) cells transfected with recombinant bovine $20{alpha}$-HSD and bovine placental tissues. According to western blot analysis, anti-$20{alpha}$-HSD specifically recognizes the 37-kDa protein bovine $20{alpha}$-HSD. The protein is not present in untransfected CHO cells. Anti-$20{alpha}$-HSD also recognizes a specific protein in the ovaries and placenta of other animals. Immunostaining was used to detect expression of bovine $20{alpha}$-HSD protein in the cultured luteal cells during the estrous cycle later.