Introduction: The aim of this study was to evaluate and compare the immunohistochemical expression of transforming growing factor beta (TGF-b) and interferon gamma (IFN-g) between radicular cysts (RCs) and dentigerous cysts (DCs). Methods: Twenty RCs and DCs were selected for analysis of the immunoexpression of TGF-b and IFN-g in the epithelium and capsule. Results: The cell reactivity of TGF-b and IFN-g in the lining epithelium and capsule of RCs showed no significant differences when compared with DCs (P > .05). There was a tendency of a higher expression of TGF-b in the capsule of DCs. Conclusions: Our results showed the presence of TGF-b and IFN-g in RCs and DCs, supporting the hypothesis that both participate in the development of these lesions, where IFN-g usually plays a role in bone resorption, which is counterbalanced by the osteoprotective activity performed by TGF-b.