We studied the effect of botulinum-A toxin on spasticity of the leg adductors in 9 patients who were either chair-bound or bed-bound with chronic stable multiple sclerosis. We injected botulinum toxin (400 mouse units) or placebo into the adductor muscles in a randomized, crossover, double-blind design. Two physicians, who were unaware of the treatment order, used an objective rating scale and independently assessed the patients; interobserver correlation was excellent (r = 0.93-0.81). We found that botulinum toxin produced a significant reduction in spasticity (p = 0.009) and a significant improvement in the ease of nursing care (p = 0.009). There were no adverse effects during this short-term trial. This is the first demonstration of the beneficial effect of botulinum toxin on focal spastic muscle contractions.