IN RECENT years interest has been concentrated on treponemal antigens and little attention has apparently been given to improvement of the currently available nontreponemal antigens. This is unfortunate, since an easily available lipoidal antigen with improved specificity would be of extreme value in the laboratory. In the United States, with its premarital and prenatal laws, millions of serologic tests for syphilis are performed on presumably healthy individuals. All too frequently, particularly with cardiolipin antigens commercially available, reactive laboratory findings are obtained which are not supported by clinical findings. Various estimates of biologic false positive reactions with routine procedures have been advanced by various authors. Variation in these figures is wide. They, of course, are influenced by the type of population group evaluated, the serologic procedures and type of antigen employed, and the definition of positivity used. Deservedly or not, the current criterion of the value of a serologic test for syphilis is its sensitivity and specificity in comparison with the sensitivity and specificity of the Tbreponema palliduim immobilization (TPI) test of Nelson and Mayer. Using the TPI test as a reference, rather high false positive figures have been found with standard lipoidal antigens. MacPherson, Ledbetter, and Martens (1) reported results of 21 to 40 percent of routine reactive tests as biologic false positives, and a number of other authors, including Moore and Lutz (2), reported 40 percent false positives, In a comparative study of 572 serums which were reactive with nontreponemal tests, Wilkinson (3) found that the Kahn test gave 17 percent nonspecific reactions, the Wassermann test with lipoidal antigen 13 percent, and the Wassermann test with cardiolipin antigen 23 percent. In 244 patients found to be seropositive on routine testing during pregnancy, blood tests of 27.5 percent gave presumed nonspecific reactions. In our own laboratory, of 796 reactive VDRL slide tests, 435, or 54.6 percent, were assumed to be biologic false positives, with the TPI test used as the reference test. Of 724 reactive cardiolipin Kolmer tests, 385, or 53.2 percent, were in the same category. These figures were obtained on specimens submitted to us for TPI tests, and these cases can consequently be placed in the problem category.