Botulinum A exotoxin was recently approved for use in Canada. We describe the efficacy of botulinum toxin in the management of 235 patients with blepharospasm (mean age 64.3 years) and 130 patients with hemifacial spasm (mean age 60.4 years) treated at three Canadian ophthalmologic centres between 1984 and 1989. A total of 98% of the patients with blepharospasm and 100% of the patients with hemifacial spasm had significant relief of their symptoms; however, 11% of the former and 2% of the latter did not respond to the usual starting concentrations of the drug and needed stronger dosages for relief. The duration of relief varied widely in both groups. Up to 7% of patients had ineffective treatments but responded to subsequent injections. Analysis of variance and linear trend statistics showed that there were no changes in the mean duration of relief over the first several treatments for individual patients in either group. Side effects were transient and included ptosis, exposure keratitis, epiphora and strabismus.