The incidence of radiation optic neuropathy (RON) after external photon beam radiation therapy for non-functioning pituitary adenoma (NFA) is not well stu-died. Retrospective review was performed of ophthalmological and imaging data in 72 patients with NFA treated between 1985 and 1998 with external beam radiation therapy following surgery. Clinical follow-up after radiation therapy had to be at least 18 months. RON was defined as a sudden and profound irreversible visual loss affecting the optic nerve or chiasm. A review of previously published cases of RON was then performed. In our cohort, no patient had RON. A total of 11 adequately documented series reports of RON were found in the medical literature on radiation-treated NFAs. The incidence of RON in NFA from these series is 0.53% (95%CI, 0.26%-0.96%). An additional 14 single RON cases have been reported, bringing the total of adequately documented RON cases to 25. RON is a rare complication after external beam radiation therapy for NFA.