Giant paranasal sinus osteomas are rare tumors that may be very closely adherent to surrounding anatomical structures, and complete removal of these tumors may be very challenging. We report 6 cases of giant paranasal sinus osteomas that were removed completely and discussed their symptoms, diagnostic workup, and our surgical approach. We reviewed the patient files of our 6 cases with giant paranasal osteomas and summarized their history, symptoms, diagnosis, management, and follow-up. Three of our patients underwent endoscopic sinus surgery; the other 2 patients underwent open surgical approach (osteoplastic flap procedure with bicoronal incision), and 1 patient underwent both endoscopic and open approaches, all under general anesthesia. Mean patient age was 42.6 years (range, 18–54 years). Main symptoms were headache, proptosis, and diplopia. Physical examination findings include proptosis and frontal puffiness. Paranasal sinus computed tomography revealed larger than 3-cm-diameter tumors in the frontal and ethmoid sinuses. The surgical approach to each case was customized to the location, size, and presenting symptoms of the osteoma. Histopathology revealed osteoma in all cases. All patients were evaluated with paranasal sinus computed tomography scan postoperatively. At a mean follow-up of 15 months, complication was observed in 1 patient; no residual tumor or recurrence was detected following surgery. In symptomatic cases with huge tumors, open, endoscopic, or combined approaches could be applied because of the location and size of the tumor with successful outcomes. Both endoscopic and open approaches are safe and effective methods for removal of these tumors.