Paranasal sinus osteoma is a slow-growing, benign, encapsulated bony tumour that may be commonly asymptomatic, being detected incidentally in 1% of plain sinus radiographs or in 3% sinus computerized tomographic scans. In a patient presenting with epiphora and nasal obstruction, computed tomography disclosed a giant osteoma of the ethmoid. In this article, one patient having giant ethmoidal osteoma with orbital extension is described, and epidemiology, diagnosis, treatment, and pathological findings in paranasal sinus osteoma are reviewed.