Fibrous dysplasia (FD) is a benign fibroosseous lesion that may progress a single or multiple bones involvement. Although it is a benign tumor, it has available malignant transformation potential. While mostly maxilla, mandible, parietal, occipital, and temporal region are stiffed in the head and neck region,the ethmoid bone involvement is very rare. This article presents an 18-year old patient who was diagnosed with fibrous dysplasia in right ethmoid sinus and had a mass in right ethmoid cells destructing lamina papyracea, which was detected in paranasal computerized tomography obtained due to complaints of pain around right eye, asymmetry between both eyes and diplopia.