Introduction: Infected tooth is a common findings in dental patients. A neglected infected tooth goes untreated the infection will spread into the root canal and further into the apex, chronically destruct the surrounding hard tissues. Inflammatory radicular cyst is one of the result of an untreated tooth infection. In this article we present a cross-sec-tional study of inflammatory radicular cyst in the jaw accompanied with their histological examination, clinical findings and their treatments. Method: Exactly 8 cases, accompanied with the available post-operation histological examination, were collected in 8 months between January – August 2019 in the Maxillofacial Surgery department in Brawijaya University Hospital (RSUB). Results: Across all 8 cases, 75% of cysts formed in the mandible, in addition the frequency of the cyst observed in the apex of the posterior tooth is 87.5%. surprisingly a moderate number of radicular cyst studied in this article is caused by an inadequate tooth restoration which leads to secondary caries (37.5%). All of the cases were in accordance with the diagnosis established by their own histological examination. Conclusion: The treatment in periapical lesion that cause bone destruction needs correlation between clinical exam-ination, radiography, and histological examination in order to properly establish the diagnosis and to improve the patient’s quality of life.