Diffuse leptomeningeal gliomatosis is a rare condition characterized by glioma in the leptomeninges without a dominant mass lesion. The difficulty in diagnosis of this condition, its rarity. and its extensive nature have hampered its successful treatment. Most cases of primary diffuse leptomeningeal gliomatosis have occurred in adults. Reported here is a case of this condition in a 9-year-old girl; to the authors' knowledge, she is the youngest patient with diffuse leptomeningeal gliomatosis and the longest survivor of the malignant variety.