Mucoceles are uncommon and the majority of cases occur in the frontoethmoidal complex. The accumulation of mucous secretion and eventual secondary infection may result in the formation of a pyocele of the middle turbinate, which is exceptionally rare. This case report presents a patient with a large pyocele of the middle turbinate invading the orbit. A 48-year-old woman presented with a three-week history of nasal obstruction, slight rhinorrhea, and headache. There was an external swelling of the nasal pyramid just near the medial canthus and right exophthalmos with bulging of the medial canthus of the ipsilateral eye. A computed tomography scan revealed a rounded, expansive lesion of soft tissue density. There was a thin compact bone at the margin. Under general anesthesia, resection of the lateral and inferior walls of the middle turbinate was performed. The large cystic mass was filled with pus. Exophthalmos and bulging of the medial canthus immediately disappeared. Histologic examination showed the mucocele wall with a ciliary respiratory epithelium.