Abstract: Antigenic compositions are disclosed for use in diagnostic kits and the like for detecting the presence of antibodies specific for Campylobacter pylori, bacteria often associated with the occurrence of Type B gastritis and peptic ulcer disease. Samples of bodily fluids, for instance, may be contacted with immobilized antigen which is then washed and tested for the occurrence of significant levels of antigen/antibody complex. Levels exceeding a predetermined positive threshold are indicative of antibodies to Campylobacter pylori in the sample tested. Kits employing the antigenic compositions of the invention preferably include means for detecting the antigen/antibody complex such as materials and reagents for conducting an enzyme-linked immunosorbent assay, Western blot technique, liposome-based assay or other known detection tests.