OBJECTIVES: The purpose of this article is to discuss the natural history, treatment, and outcomes for patients with aneurysmal bone cysts (ABC). METHODS: Review of the pertinent literature. RESULTS: ABCs account for 1% to 2% of all primary bone tumors, usually present in the first 2 decades of life, and exhibit a slight female preponderance. The majority of patients are treated with curettage with local control rates ranging from approximately 70% to 90%. Almost all patients with recurrences are salvaged by one or more additional operations. A small subset of patients is treated with marginal or wide excision and almost all are locally controlled. A few patients with incompletely resectable, aggressive, and/or recurrent ABCs are treated with low-dose (26-30 Gy) radiotherapy (RT) and are locally controlled in approximately 90% of cases. CONCLUSIONS: The mainstay of treatment is surgery and most patients are cured with one or more operations. A small subset of patients with incompletely resectable, aggressive, and/or recurrent ABCs may be cured with low-dose RT.