Schwannomas are benign tumors that are rarely found in the sinonasal cavity, and the purpose of this study was to characterize the CT and MR imaging findings of 12 patients with surgically proved sinonasal schwannomas. Assessed features include location, margin, shape, size, internal architecture, pattern and degree of enhancement, and associated bony wall changes. The characteristic CT and MR imaging findings of sinonasal schwannoma include a well-defined soft-tissue mass, most frequently occurring in the nasal cavity and ethmoid sinus with pressure remodeling of the adjacent bony wall. The tumors were isoattenuating on CT and predominantly isointense on both T1- and T2-weighted MR images, compared with the brain stem. Mild contrast enhancement on CT and strong enhancement on MR images were also demonstrated in most of the tumors, and cystic or hemorrhagic changes were noted in 2 cases.