Apical periodontitis is produced in the majority of cases by intraradicular infection. Treatment consists in the elimination of the infectious agents by endodontia. Even when carrying out a correct cleansing and filling of canals, it is possible that periapical periodontitis will persist in the form of an asymptomatic radiolucency, giving rise to the post-endodontic periapical lesion. The chronic inflammatory periapical lesion is the most common pathology found in relation to alveolar bone of the jaw. From the histological point of view, it can be classified as chronic periapical periodontitis (periapical granuloma), radicular cyst, and as scar tissue. The most frequent is the periapical granuloma, constituted by a mass of chronic inflammatory tissue, in which isolated nests of epithelium can be found. The radicular cyst is characterized by the presence of a cavity, partially or wholly lined by epithelium. Scar tissue is a reparative response by the body, producing fibrous connective tissue. The aim of this study is to review and update the etiopathogenic and histological aspects of chronic post-endodontic periapical lesions.