PURPOSE: To report a case of Horner syndrome that occurred after implantation of a vagus nerve stimulator. METHODS: Case report. RESULTS: A 6-year-old female with cerebral dysgenesis and intractable partial seizures presented with Horner syndrome after vagus nerve stimulator implantation. CONCLUSION: Horner syndrome can occur as a result of the vagus nerve stimulator implant procedure and should be included as one of its possible surgical complications. (Am J Ophthalmol 2001;131:383-384, (C) 2001 by Elsevier Science Inc, All rights reserved.).