Paranasal sinus osteoma is a slow-growing, benign, encapsulated bony tumor that may be commonly asymptomatic, being detected incidentally in 1% of plain sinus radiographs or in 3% of sinus computerized tomographic scans. In a patient presenting with orbital cellulitis and epiphora, computed tomography disclosed a large osteoma of the ethmoid sinus. Excision of the osteoma allowed recovery of vision, return of extraocular muscle function, and resolution of choroidal folds. Proptosis, diplopia, and visual loss are other frequent presenting signs of paranasal osteomas. Epidemiology, diagnosis, treatment, and pathologic findings in paranasal sinus osteoma are reviewed.