Endoscopic techniques have been applied to oral and maxillofacial surgeries. Previous studies have proved their practicability in the treatment of osteomyelitis of the mandible and displaced residual roots in the maxillary sinus. In this report, two patients with dentigerous cysts in the maxillary sinus underwent endoscope-assisted curettage. Both patients were successfully cured without recurrent lesions or any complications. The follow-up found that the bone cavities had shrunk. An endoscope-assisted Caldwell-Luc operation provided clear visibility of the surgical field and preserved the mucosa of the maxillary sinus. Keywords: Caldwell-Luc operation, dentigerous cyst, endoscopic-assisted surgery, maxillary sinus