We report the appearance of gliomas of the optic nerve or chiasm in four young children with neurofibromatosis type 1 whose previous neuroimaging studies showed no abnormalities; the age range of the children was 1 year 8 months to 5 years 9 months at the time the tumors were detected. Normal neuroimaging findings in an infant or young child with neurofibromatosis type 1 does not provide assurance that the optic nerves and chiasm will remain healthy.