THE FIELD of multiple sclerosis (MS) is well into its first decade of having an effective treatment, in the form of interferon beta-1b, for beneficially modifying the natural history of relapsing-remitting MS. By reducing the number of relapses, by lessening their severity, by reducing the appearance of new areas of damage seen on cranial magnetic resonance imaging, and, possibly, by delaying the onset of progressive disability, interferon beta-1b, has generated interest and expertise in the treatment of MS and has raised expectations of further improvements in its management. The subsequent introductions of 2 recombinant proteins, both of which are interferon beta-1a products, and a random copolymer, glatiramer acetate, all of which are also approved for treating relapsing-remitting MS, have been encouraging developments in the evolving process to effectively control a common disease, such as MS, in which the etiology and pathogenesis remain ill defined.