Gliosarcoma (GS) is a rarely seen form of glioblastoma. These tumors are mostly seen in males older than 60 years of age. It isextremely rare in pediatric central nervous system (CNS) tumors. In this case report, we present a 3-year-old boy with a giantgliosarcoma. Magnetic resonance (MR) imaging and histopathologic findings are discussed. A 3 year-old boy with a clinicallydiagnosed NF-1 was admitted to the emergency department with a complaint of intractable vomiting. Magnetic resonance imaging(MRI) of the brain was suggestive of a large lobulated mass lesion in the left parietal lobe extending to the vertex and slightlycompressing the left lateral ventricle. The final histopathologic diagnosis of the tumor was considered as gliosarcoma. To ourknowledge, this case constitutes the first youngest case with neurofibromatosis type 1 reported in the literature in all pediatric casesof GS.