Over a 24-year period, optic gliomas were found in 29 children, 16 of whom had neurofibromatosis type 1 (NF-1). These 16 children comprised 21% of all children referred for management of NF-1 and its complications. The finding of optic glioma led to the diagnosis of NF-1 in 4 children. The mean age at diagnosis of optic glioma in NF-1 children was 6.4 years, and the average estimated duration of visual symptoms prior to diagnosis was 2.1 years. Most optic gliomas in NF-1 children were ascertained because of a visual complaint (69%), and an even greater number of children (88%) had an abnormal ophthalmological examination. The optic chiasm was involved in 75% of the patients. All of the seven children with optic glioma examined by visual evoked potential had an abnormal response ipsilateral to the tumour. The majority of the children received radiation therapy. After a mean follow up period of 5.8 years no deaths had occurred due to optic glioma, but in 35% of the children vision was worse. We conclude that optic glioma is a common, serious complication in NF-1 children. Routine care of such patients should include regular noninvasive investigations aimed at detecting lesions of the optic pathway.