Aneurysmal bone cysts (ABCs) are destructive cystic lesions of the bone and are common in children. They are expansile in nature and, therefore, may become symptomatic. These have traditionally been treated surgically; but recently, endovascular embolization has shown promise as a stand-alone therapy. The authors describe a case of an ABC highlighting the effectiveness and efficiency of endovascular treatment. A 16-year-old boy was referred for a 4-month history of radiating back pain and urinary hesitancy. Findings from his neurological examination were normal, but he had problems ambulating because of pain. Magnetic resonance imaging and CT scanning showed a cystic mass in the sacrum; a biopsy was performed and diagnosis of ABC was confirmed. Treatment options were then discussed with the family. The patient underwent 2 endovascular embolizations in approximately 1 month: Onyx 18 was involved in the first session, and N-butyl cyanoacrylate glue was used in the second session. After the first treatment, the patient experienced a dramatic decrease in pain and concomitant improvement in function. The patient went from being mildly symptomatic after the first treatment to completely asymptomatic after the second treatment. Clinical and radiographic follow-up obtained at 2, 6, and 18 months after initial treatment revealed the patient to be asymptomatic with progressive ossification. Endovascular treatment can be effective in treating symptomatic cases of ABC in which surgery would carry significant risk. Selective arterial embolization can promote sclerosis and result in an immediate and significant decrease in pain.