BACKGROUND AND PURPOSE: To report on the efficacy and follow-up of 23 patients with primary optic nerve sheath meningioma (ONSM) with fractionated stereotactic conformal radiotherapy (SCRT). PATIENTS AND METHODS: Between 1996 and 2003, 23 patients ( = 23 eyes) with ONSM were treated. Indications for primary stereotactic radiotherapy were tumour progression documented by imaging or symptoms (loss of vision, pain). All patients received SCRT with a median dose of 50.4Gy in 6 weeks. RESULTS: After a median follow-up of 20 months (1-68 months) a 95% (21 of 22) visual control was seen: vision improved in 16 patients and remained stable in 5. For 13/16 patients improvement was documented already within 1-3 months after SCRT. Vision became worse in one patient. An improvement of pain was observed after radiotherapy in 6 patients as well as of proptosis in 1 patient. For 1 patient pain was persistent after SCRT. In one patient 4 years after SCRT a radiation retinitis and vitreous haemorrhage was seen. CONCLUSIONS: Fractionated stereotactic radiotherapy improves vision, often shortly after treatment, and is thus a viable treatment option for this tumour entity.