Multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system. It results from an autoimmune response against one of several antigens of cerebral white matter tissue. The pathogenesis of MS lesions consists in migration of auto-reactive T-cells and disruption of the blood-brain-barrier. B-cells and their products are, however, also important for demyelination together with various cytotoxic or pro-inflammatory cytokines. Recent advances in immunology and biotechnology and protein engineering techniques have opened the door for novel immunotherapies. Immune modulation with beta-interferon has shown beneficial effect, both in relapsing remitting and secondary progressive multiple sclerosis.