The dentigerous cyst develops as the result of an alteration of the enamel epithelium in the crown of tooth. In a certain cases it could be found in the maxillary antrum with unerupted tooth within it under the influence of infection or hereditary cause. Possible chances to be malignant or chronic inflammatory disease in the maxillary antrum are our interest in the case of dentigerous cyst. Recently, the authors have experienced two cases of dentigerous cyst in the maxillary sinus with chronic inflammation which have regularily or irregularily arranged usual numbers of teeth. The cysts and teeth were completely removed under local anesthesia by Calewell-Luc's approach.