A radiologic study of 139 dentigerous cysts (128 patients) indicated the followings: 1. There was higher incidence in males (62.99%) than in females (37.01%). The most common age group was 11-20 years and the average age was 23.6 years. 2. The most common clinical symptoms was swelling of the jaws (49 cases, 33.09%), and no symptoms was presented in 26 cases (18.71%). 3. Dentigerous cysts were found to be slightly more common in the maxilla (53.24%) than in the mandible (46.76%) and there was almost no difference in occurance between right and left side. The maxillary supernumerary tooth was the most frequent site of the dentigerous cyst and no dentigerous cyst was found to be related to a deciduous tooth. 4. The most common radiographic findings was root resorption of the adjacent teeth (33.09%), and the central dentigerous cysts were 78 cases (56.12%), the lateral dentigerous cysts were 61 cases (43.88%). 5. The increased radiolucency at the crown portion of the tooth in a cystic cavity was seen in 44 cases (31.65%), and a case of dentigerous cyst was found in a edentulous patient, and 16 cases of multiple dentigerous cysts were found in 5 patients. 6. The ameloblastic changes in 8 cases, the keratinization of the cyst wall in 2 cases, and a case of epidermoid carcinoma were confirmed microscopically.