The etiology of multiple sclerosis (MS) remains unclear. To determine if autoantibodies to myelin basic protein (MBP) are produced during parvovirus B19 infection, a competitive ELISA was performed using plasma from MS patients exhibiting high IgG titers for parvovirus. Our results showed the addition of MBP decreased the binding of IgG to B19 antigen in a dose dependent fashion suggesting a possible link between parvovirus B19 and a subset of patients with clinical MS.