Introduction rnFibrous dysplasia(FD)is a sporadic skeletal disorder in which normal bone structures and marrow are replaced by fibro-osseous tissue[1].It is classified into three types:monostotic FD,polyostotic FD,and McCune-Albright syndrome[2].The monostotic iS the most commen form of FD.The disease primarily affects the long bones of the patients,and may also develop in the craniofacial region.However,FD in the paranasal sinuses is uncommon.The case in this report was diagnosed as FD in the ethmoid sinus which is a rarely seen case.