Central giant cell granuloma (CGCG) of the jaws is a central osteolytic lesion characterized histologically by multinucleated giant cells in a background of ovoid to spindle-shaped mesenchymal cells. Whether CGCG is a reactive lesion or a truly benign neoplasm remains undetermined, and the mechanism determining the onset of the disease remains unknown. To have more information regarding the genetic events involved in CGCG, the authors decided to perform an expression profile. Samples were derived from two surgically resected CGCG of the mandible. RNA extracted from a pool of three normal bone tissues was used as control. By using DNA microarrays containing 19,200 genes, the authors identified several genes whose expression was significantly up- or down-regulated. The differentially expressed genes cover a broad range of functional activities: cell cycle regulation; signal transduction; and vesicular transport. It was also possible to detect some genes whose function is unknown. The authors believe the data reported to be the first genetic portrait of CGCG of the jaws. Several markers have been identified that can potentially help in identifying some biological behavior (ie, quiescent versus aggressive lesions), as well as genes whose products could be potentially disease-specific targets for therapy. However, the authors think that more cases are needed, especially those comparing quiescent and aggressive lesions, before the exact profile of CGCG is known.