The natural history of 33 optic pathway tumors (OPT) diagnosed in 227 children with neurofibromatosis type 1 (NF-1) seen in a specialty clinic was evaluated in a prospective, longitudinal study at Children’s Memorial Hospital and Northwestern University Medical School, Chicago. OPTs were found in 19% of 176 who had CT or MRI at a median age of 4.2 years. No OPT developed on later follow-up in children who had not received an MRI. In those without ophthalmological complaints at diagnosis, the incidence of OPT was 15%. The median age of children with ophthalmologic complaints such as proptosis or glaucoma (1.9 years) was significantly lower than that of children without such complaints (5.3 years). Only 8 tumors were discovered because of visual complaints or precocious puberty; 25 (76%) children were asymptomatic at time of diagnosis, and 21 (64%) had normal eye findings. Six with chiasmal tumors had decreased visual acuity without proptosis. At follow-up of 0.2 - 8 years, only 3 (9%) showed progressive tumor growth on MRI or deteriorating vision after diagnosis. Symptomatic OPT were diagnosed before the age of 6 years. [1]