-Objectives:Primary aim is to quantify the success rate of periapical surgery. Secondary objectives include the determination of the histological nature of the lesions, and the incidence of the different teeth on which this surgery is performed. Study design: This is a prospective cohort study conducted in one centre. The same operator following a standardized surgical protocol performed all surgeries. Follow-up (including clinical examination and periapical X-ray) was conducted at day 7, and months 6, 12 and 18. Statistical analysis included determination of the mean, standard deviation and paired two-tailed Student's t-test, for each of the variables. Results: 132 periapical surgeries were performed on 114 patients. Success and failure rate at 18 months, are 90%, and 6%, and uncertain in 4%. Histopathology confirmed that 72% of the lesions were granulomas, and 28% cysts. Periapical surgery pertains mostly to maxillary (70%) and posterior teeth (70%). Conclusion: Prognosis of conventional periapical surgery is very good. Failure rate peaks at 7 months, written informed consent is paramount.A radiolucent apex after endodontic treatment is a common finding with up to 45% of the treated teeth in certain studies [1,2]. These lesions can be found during a routine check-up, or during an emergency appointment when associated with pain. As orofacial pain is ascribed to periapical abscesses in 25% of the patients [3], these periapical radiolucencies, in the context of periapical surgery, can be a diagnostic challenge. Periapical abscesses are the consequence of a bacterial infection of the root canals [4]. Treatment classically consists of the elimination of necrotic and infected tissue, followed by obturation of the root canal system and a sealed restoration of the crown. Periapical surgery is indicated when root canal retreatment has failed or is contraindicated [4]. An osteo-mucoperiosteal flap followed by the appropriate osteotomy allows access to the apex of the tooth. The lesion is removed and the root canal system sealed [4]. Success rates reported vary between 40% [5] and 97% [6]. Correspondence: alpalantar@wanadoo.fr The main objective of this study is to assess the success rate of periapical surgery using a standardized protocol. Secondary objectives include the determination of the histological appearance of the lesions (granulomas or cysts), the incidence of the different teeth on which this surgery is performed, and the recurrence frequency.