Borreliacidal antibodies participate in the resolution of Lyme disease by clearing Borrelia burgdorferi sensu lato from the host. Detection of borreliacidal antibodies is also valuable for determination of the specific serodiagnosis of Lyme disease. We show in this work that antibody detected by the borreliacidal antibody test did not correlate with antibody detected by the indirect fluorescent-antibody assay or Western immunoblotting. Detection of borreliacidal antibody decreased with elimination of the spirochete from the host in the presence or absence of therapy. By contrast, the antibody responses detected by the indirect fluorescent-antibody assay or Western immunoblotting remained elevated or continued to expand, respectively. This suggests that the borreliacidal antibody test is a prognostic indicator for clearance of the spirochete. Additional investigations with humans are needed to confirm the prognostic potential of the borreliacidal antibody test.