Gas within the cavernous sinus is an unusual finding. We report three patients who demonstrated gas in the cavernous sinus on computerized tomography (CT). The clinical information of these patients was reviewed for the possible source of the gas and the symptoms induced by the gas. Cavernous sinus gas was seen in two patients with sphenoid sinus fracture and in one patient after intravenous fluid infusion. None of the patients had symptoms referable to the cavernous sinus gas, but one patient had a grave prognosis due to trauma. Identification of cavernous sinus gas on CT and correlation with the clinical information is mandatory for further management.