Maxillary sinus mucoceles are relatively rare, accounting for 10% or less of all mucoceles of the paranasal sinuses in the United States and Europe. Few individual cases have been reported in the literature. A mucocele of the paranasal sinus is an epithelial-lined cavity containing mucus. The most common causes of mucoceles are previous surgery, trauma, chronic infection, and allergic sinonasal disease. We herein present a 42 year-old woman with aspergillosis superimposed in her maxillary sinus mucocele. On presentation, this patient had a 10-year history of intermittent right nasal obstruction that had became progressively more severe recently. The preoperative CT scanning showed opacification and smooth expansion of the right maxillary sinus, suggesting the exsistence of a muco-cele. In endoscopic operation, a yellowish mycolith was found within the mucocele which was opened and drained. The postoperative course was smooth and the nasal symptoms improved. It is likely that this mucocele arose from blockage of the outflow tract of the maxillary sinus by a mycolith.