Reduction malarplasty for patients with a prominent malar complex is a popular procedure in Asia. However, a range of complications have been reported after reduction malarplasty, such as hematoma, orbital complications, asymmetric face, and nonunion. A medially displaced fracture or bony fragment can induce sinusitis and subsequent trauma to bones in combination with chronic inflammatory processes, which can lead to chronic obstruction of mucus-secreting glands. In our case, 46-year-old man presented with a large mucocele in the maxillary sinus after malar reduction approximately 20 years ago.