Central Giant Cell Lesion (CGCL) is an uncommon benign jaw lesion, with uncertain etiology, and a variable clinical behavior. Studies of molecular markers of CGCL, may help understanding better the nature and behavior of this lesion, and eventually may represent a definitive target to pharmacological approach in the treatment of CGCL. Chronic inflammation has been found to mediate a wide variety of diseases including neoplasms. Among the gene products involved in the induction of the inflammatory process, Cyclooxygenase 2 (COX-2) has been shown to have a close relationship with tumorigenesis, however COX-2 expression has never been evaluated in CGCL. The aim of the study was to investigate the expression of COX-2 in CGCL. Immunohistochemical assessment for COX-2 expression was performed in 18 patients previously diagnosed with CGCL. Multinucleated giant cells (MGC) and mononucleated stromal cells (MSC) were used in the slide analysis. Among the patients studied, 10 were male and 8 were female, with a median age of 15.4 years. Lesions in the mandible were observed in 11 cases and 7 were found in the maxilla. There were 9 aggressive and 9 non-aggressive CGCLs. COX-2 immunopositivity was present in only 3 cases stained in both MGC and MSC. All 3 cases presented with ulcerations in the mucosa lesion, suggesting that the COX-2 expression is due to the presence of inflammation. This study does not support the involvement of COX-2 in the etiophatogenesis of CGCL.