Baclofen is a safe and effective means for treating spasticity associated with multiple sclerosis. We found no toxic effects on hepatologic, hematopoietic, or renal function, acutely or for over 3 years of follow-up. A statistically significant reduction was noted in frequency of spasms, and clonus, and there was improved range of joint movement, which enabled patients to maintain functional status for prolonged periods. For the more disabled patients, treatment with baclofen gave symptomatic relief of painful spasms and made immobility more tolerable. Optimum effect was achieved when baclofen was administered in the early stages of disease, before major disabilities became permanent.