Alum precipitatedBacteroides nodosus vaccines prepared from two antigens with and without the saponin derivative, Quil A, did not induce adverse tissue reactions in sheep injected subcutaneously. Vaccinated, non-infected Merino sheep had higher agglutinin antibody titres when the vaccines included Quil A. Moreover, the recovery rates in vaccinated sheep affected with foot-rot were higher when the vaccines included Quil A.