The aim of this paper was to search for reported cases of sinus infection following reduction malarplasty and present guidelines for the prevention of sinusitis. Two cases of maxillary sinusitis that developed after reduction malarplasty has been reported, which were treated with endoscopic sinus surgery. Histologically, thickness of the mucosal lining of the maxillary sinus (Schneiderian membrane) was 0.41 mm at sinus floor, and 0.38 mm at 2 mm above the floor. In functional endoscopic sinus surgery (FESS), the uncinate process is removed, exposing the hiatus semilunaris. The anterior ethmoid air cells are opened, allowing better ventilation but leaving the bone covered with mucosa. FESS improves the function of the osteomeatal complex and therefore provides better ventilation of the sinuses. In odontogenic maxillary sinusitis, regeneration of the mucosal lining (ciliated epithelium regeneration and bone healing) was achieved in 1.4±1.2 years after modified endoscopic sinus surgery. In in zygomatic implant surgery, 12.3% patients presented maxillary sinusitis, and the most common treatment was antibiotics alone or combined with FESS. To prevent sinusitis after reduction malarplasty, accurate osteotomy and fixation are needed, especially when using only an intraoral incision. After surgery, radiological examinations (Water’s view, computed tomography if needed) should be performed as part of follow-up. Prophylactic antibiotics (macrolides) are recommended for 1 week if the sinus wall is opened. If swelling or air-fluid level persists, re-exploration and drainage should be performed. In patients with risk factors such as age, comorbidities, smoking, nasal septal deviation, or other anatomical variants, simultaneous FESS is suggested.