Fifty-seven patients with optic gliomas, treated by megavoltage radiotherapy between May 1970 and March 1986, are retrospectively analyzed. The mean follow-up was 7.5 years (2.5-16.5). At presentation, 46% were under 10 years old, 40% had neurofibromatosis, and 51% had neurological and/or endocrinological signs. Twenty-one tumors (37%) were confined to the optic chiasm, and 36 tumors (63%) extended to the hypothalamus, the posterior optic tract, or the adjacent brain. Two among the 16 biopsy-proven tumors were high grade gliomas. Delivered tumor doses were 40 to 60 Gy in 5 to 7 weeks. Forty-nine patients were alive (five with tumor evolution) and eight had died (five from the tumor, one from cerebrovascular complication, two from intercurrent disease). Overall actuarial survival was 83.5% at 5 and 10 years. Control of the disease in 53 evaluables patients was: complete response in 8 (15%), partial response in 25 (46%), and no progression in 12 (22%). Progressive disease was observed in three patients and signs evocative of recurrence in five others. Stabilization of visual impairment or improvement of vision was recorded in 93% of patients who were evaluable. A critical review of the literature is presented and complications discussed. Radiotherapy seems thus effective in chiasmal gliomas and must be delivered in cases of rapidly developing symptoms visual, neurological, or endocrine.