In the current report, the authors present a case of optic nerve glioma treated with fractionated stereotactic radiotherapy (FSRT). An 11-year-old girl was referred to our clinic with increasing proptosis over a 1-year period. At that time orbital MRI revealed a 20 × 17–mm mass in the right retroorbital lipomatous tissue, and FSRT was delivered to the tumor using the CyberKnife. During the 1.5-year follow-up, ophthalmological examinations did not indicate any treatment-related severe toxicity, and posttreatment MRI demonstrated marked regression of the lesion to 13 × 10 mm. Given the scarcity of reports on this subject, the authors support more extended studies of the CyberKnife for the effective treatment of this relatively common childhood tumor.