Our aim was to determine the rate of focal lesions of the corpus callosum in children with neurofibromatosis type 1, and to characterize their natural history. Magnetic resonance imaging scans of the brain in 79 children with neurofibromatosis type 1 who were followed at the Neurology Clinic of Schneider Children's Medical Center (Petah Tiqwa, Israel) from 1990-2005 were reviewed. Focal lesions of the corpus callosum were identified in 11 (14%). These included unidentified bright objects in 7 patients (9%), and a neoplastic process in 4 (5%). Follow-up ranged from 1-16 years. Two of 4 tumors had enlarged during follow-up, and one was excised. Neurofibromatosis type 1 may be associated with a 14% prevalence of corpus callosum lesions. Owing to the apparently high frequency of callosal neoplasms in this population (5% in our series), and their tendency to enlarge, careful evaluation and prolonged follow-up are warranted.