The author studied the age distribution, etiology, affected site and several radiographic features of periapical granulomas, cysts, and abscesses. The material consisted of 928 films obtained from the patients who were diagnosed and treated under the diagnosis of periapical granulomas, cysts, and abscesses during the past 8 years (1979-1986) at the Infirmary of Dental School, Chosun University. The obtained results were as follows: 1. The order of incidence was as follows: periapical abscess (67.2%), granuloma, and cyst. 2. The age distribution revealed the highest incidence around the age of 30 and relatively higher incidence over the age of 60 in the case of periapical abscess and granuloma. 3. In the frequency of location: Periapical abscesses occured most frequently in the mandibular molars. Granulomas showed relatively higher incidence in maxilla than in mandible. Cysts were most common in the maxillary anterior teeth. 4. The mean diameter of dental granuloma was 5.9㎜, however, all dental granulomas were less than 9.3㎜ in diameter. The mean diameter of periapical cyst was l3.8㎜. 5. Periapical cyst revealed well circumscribed radiolucent lesions and 77.8% of the lesion showed white line. 86.0% of dental granuloma showed well circumscribed border, 54.5% sclerosis on surrounding bone and 38.5% partial white line. Periapical abscess revealed diffuse radiolucent lesion, 89.6% of the lesions had sclerosis on surrounding bone, and 38.0% sinus tract.