In two recent articles published in Molecular Immunology, Steere and colleagues continue their search for an autoimmune mechanism of arthritis in patients who have failed short-course antibiotic therapy for Borrelia burgdorferi, the spirochetal agent of Lyme disease. As in previous attempts, the authors fail to elucidate a molecular mimicry mechanism for the putative autoimmune process, leading to the conclusion that there is no credible scientific evidence for a post-infectious autoimmune mechanism of arthritis in chronic Lyme disease.