Abstract: Objective To study the x-ray and CT findings of mucoceles of frontal and ethmoid sinuses and their value of diagnosis. Methods Twelve cases including fifteen mucoceles were studied. X-ray film and CT were performed in all cases .X-ray and CT findings were analyzed and correlated with operative findings. Results Of 15 mucoceles, 9 were found in ethmoid sinuses, 6 in frontal sinuses. Density of sinuses cavity increase in all cases .Sinus expansion, thinning of sinus wall and bony defect were found on X-ray film .CT showed low density with respect to muscle in 11 sinuses, identical in 3 and high density in one case and periphral sinus mucoca enhencement in 3 cases .Sinus expansion and thinning of the sinus wall were found in all cases, the configuration of mucoceles is smooth and clear.Bony defect is obvious in 9 mucoceles and mucoceles invade into adjacent consturctions. Conclusions CT can accuratelly display the bony change and characteristic findings of mucocele and play an important role in diagnosis and differential diagnosis