Extensive research is under way to develop pharmacotherapeutic agents that will prevent the exacerbations and the progression of neurologic disability associated with multiple sclerosis (MS). The most intensive research strategy has involved agents intended to limit demyelination by reducing inflammation and modifying the immune response. In this category are interferon beta-1b, the first compound approved for use outside of clinical trials; interferon beta-1a; and copolymer 1. Experimental agents include other interferons, methotrexate, linomide, monoclonal antibodies, T-cell receptor peptides, and 2-chlorodeoxyadenosine. Although they have been used effectively to treat exacerbations of MS, corticosteroids and corticotropin are now under evaluation as disease-modifying agents. A second strategy, enhancing remyelination by limiting demyelination and oligodendrocyte injury, is represented by protein growth factors. A third therapeutic approach, improving conduction in demyelinated fibers, is represented by the potassium channel blockers 4-aminopyridine and 3,4-diaminopyridine.