Forty-eight patients were given serial injections of botulinum toxin in their eyelids for treatment of eyelid spasm during a two-year interval. Ninety-four percent obtained relief of spasm from botulinum toxin injection. The duration of the spasm-free interval as well as the incidence of ptosis and of diplopia was dose dependent. The marked increase in the incidence of these side effects with only a small increase in the duration of the spasm-free interval, when a dose of 25 units per lid was used, leads the authors to conclude that this dose is too high and should not be used. Since diplopia was most commonly caused by paresis of the inferior oblique muscle, and since blepharospasm usually can be controlled by excising the upper lid protractors, further studies are required to determine whether lower lid injection is necessary and, if it is found to be so, whether injecting only the lateral portion of the lid would be adequate.