Medical treatment of dystonia usually results in an incomplete response and is frequently unsuccessful. Peripheral surgical therapy is available for some focal dystonias, but may only offer temporary relief and may have unacceptable complications. We have used local injections of botulinum toxin into the appropriate muscles for treatment of disabling focal or segmental dystonia in 93 patients with torticollis, blepharospasm, oromandibular dystonia (OMD), limb dystonia, lingual dystonia, and dystonia adductor dysphonia, in addition to four patients with hemifacial spasm. Significant relief of motor symptoms was seen in 69% of the patients with blepharospasm and 64% of patients with torticollis; 74% of the latter group with pain experience relief. Relief of symptoms was noted in most patients with OMD and limb dystonia, and all with lingual dystonia, dystonic adductor spastic dysphonia, and those with hemifacial spasm. Benefit averaged 2 1/2-3 months initially; however some patients experienced longer relief with subsequent injections. Adverse effects were transient, although 2 patients developed antibodies against the toxin, and we documented evidence for distant effects in others. This approach of chemically weakening contracting muscles in focal dystonia offers many advantages over pharmacotherapy and surgical therapy. Additional experience is needed to explore the proper doses, and potential for long term adverse effects.