Clostridium difficile toxin A (TcdA) monoclonal and polyclonal antibodies were produced for use by the USDA-Center for Veterinary Biologics (CVB) in anticipation of vaccine product licensing requests. The Virus-Serum-Toxin Act which requires potency evaluation of bacterins prior to sale is implemented by the CVB which makes the production of reagents necessary for product testing. The monoclonal antibody was isotyped and determined to be IgG1, κ. The antibodies were also tested using indirect enzyme-linked immunosorbent assay (ELISA), sandwich ELISA, western blot and toxin neutralization tests to check for the neutralizing effects they had on TcdA. Both the Mab and Pab had neutralizing activity against TcdA in mice and they reacted with TcdA in western blots and ELISA. The Pab reacted with TcdA in the sandwich ELISA and neutralized the toxin in mice. The Pab was also shown to be specific for TcdA in mouse tests because it would not neutralize crude C. difficile toxin which contained TcdB as well. Both antisera reacted with native (non-denatured) Clostridium sordellii toxin HT (TcsH) in ELISA.