Myelin oligodendrocyte glycoprotein (MOG) induced experimental allergic encephalomyelitis (EAE) is an animal model for the central nervous system disease multiple sclerosis (MS). The roles of individual components of the immune system have not been completely defined in the mouse model, and to determine the role of B cells and Abs in the induction of EAE and demyelination, B cell-deficient μMT (H-2 b) mice were immunized with MOG peptide 35–55. The μMT mice were susceptible to MOG-induced EAE and developed a chronic sustained disease, with inflammatory lesions and primary demyelination in the spinal cord, brain, and optic nerves, similar to that seen in wild-type C57BL/6 mice. The inflammatory cells in the central nervous system of μMT mice included both activated and memory T cells and macrophages. The data suggest that B cells and Abs are not necessary for primary demyelination in MOG-induced EAE in mice.