Multiple sclerosis, a chronic demyelinating disease of the CNS, is now a treatable disease. Phase III clinical trials of three recombinant IFN-beta products conducted in relapsing-remitting multiple sclerosis have shown, albeit modest, significant effects on relapses and short-term progression of disability, and a more substantial effect on MRI parameters. However, these effects do not correlate well with clinical disease activity or long-term disability. Overall, IFN-beta is safe and generally well tolerated, and reported adverse events were comparable between preparations. Systemic side effects can be effectively managed by dose escalation, use of an auto-injector and careful clinical monitoring.