Odontogenic myxoma (OM) is a rare and locally benign neoplasm of high aggressive behavior found exclusively in the jaws. OM commonly occurs in the second and third decade, its quite rare to find in maxilla that to invading the maxillary sinus completely. The lesion often grows without symptoms and presents as a painless swelling. The radiographic features are variable, and the diagnosis is therefore not easy. This article presents a case of OM of maxilla in a 13-year-old boy, which was previously diagnosed as fibrosseous lesion with the help of CT.