As endoscopic sinus surgery has been used widely in sinus pathologies and advancements in computerized tomography technologies, the importance of the lateral nasal wall anatomy and its variations has been emphasized more commonly. In evaluation of endoscopic and radiological anatomy of paranasal sinuses attention must be paid to these variations. Concha bullosa which is an anatomical variation of paranasal region, is pneumatization of middle conchal bone. Concha bullosa can be uni- or bilateral and if it is unilateral, it is accompanied usually by a contralateral septal deviation. Ethmoid bulla is an anterior ethmoidal cell. Its size, shape and drainage may show differences among people. In this case we present a big ethmoid bulla invaginating into a giant concha bullosa.