INTRODUCTION: Cerebrovascular diseases are rarely seen in neurofibromatosis type 1. These include vascular occlusive disease, moyamoya vessels, aneurysms, arteriovenous malformations and fistulae. CASE REPORT: We describe the case of an infant with genetically proven neurofibromatosis type 1 and progressive brain hemiatrophy over months, due to primary narrowing of intracranial carotid artery branches, as demonstrated by successive brain imaging. She presented with refractory seizures and a progressive hemiparesis associated with developmental delay. Surgical material from hemispherotomy done at 18 months showed severe abnormalities of the small vessels. CONCLUSION: Cerebrovascular changes seen in neurofibromatosis can be diffuse and progressive, with secondary hemiparesis, epilepsy and developmental delay.