Fourteen cases of mucocele of the sphenoid sinus are reviewed to assess differentiating radiographic features. Recognition is usually possible using detailed tomography in the frontal, lateral, and submentovertex projections. Two constant findings were opacification of the sinus (usually bilateral) and expansion and thinning of the sinus walls. Contiguous opacification of the ethmoid sinuses was present in most cases, and pansinusitis was frequent. Distinction from intrasellar lesions is based on the absence of sellar enlargement. Early and correct diagnosis is important to prevent permanent visual loss and to assure appropriate surgical approach.