Purified Clostridium difficile toxins A & B and toxoids A & B have been released for use by in vitro diagnostic manufacturers and researchers as immunogens, positive controls, or for determining clinical assay range. To satisfy a range of IVD applications, in particular the increasing diagnostic trend to test for both pathogenic strains of C. difficle, the toxins and toxoids are offered as separate preparations. Each is available either frozen or lyophilized and in a choice of vial sizes.