The authors report 2 consecutive adult male patients, aged 61 and 38 years, who presented with painless unilateral proptosis. Their past medical histories were negative for asthma, allergies, and Graves disease. On examination, the nose bridge of the eldest patient was clearly enlarged. Computed tomography scans of the orbits and paranasal sinuses showed in both patients the same radiologic pattern of hyperdense ethmoidal opacifications and expansion of the inferomedial orbital floor. Histopathological analysis of the ethmoidal cells mucosa obtained during inferomedial decompression revealed benign sinonasal polyposis. These cases demonstrate that asymptomatic sinonasal polyposis can be a rare cause of proptosis.