Solitary bone cysts (SBCs) of the jaws are often polymorphic, show scalloped borders when located between the teeth roots, are devoid of an epithelial lining, and are usually empty or contain blood or a straw-colored fluid. The numerous synonyms referring to these lesions reflect their uncertain nature (eg, traumatic bone cyst, simple bone cyst). SBC, also found in other skeletal locations, is often suspected after epidemiologic and radiologic test results and confirmed at surgery. Histology usually shows fibrous connective tissue or only bone. The various etiologic elements responsible for SBC include tumor degeneration, trauma, or abnormalities during bone growth. The pathogenesis of the SBC is unknown, but it is widely accepted that it could be the result of a vascular dysfunction leading to a local posthemorrhagic ischemia, inducing an osseous aseptic necrosis. This article reviews likely but still-debated etiopathogenic hypotheses of lesions of the jaws and other, more frequent bony locations, such as the humeral and femoral metaphysis.