Radicular cyst is a lesion of inflammatory nature that represents the most common odontogenic cyst. It has a frequency rate of 7-54% among the periapical radioluscences. Typically, the lesion is asymptomatic, usually located in the anterior maxilla and in most of the times ranging from 5 mm to 1.5 cm. In extensive lesions, when they occur, one can observe swelling, tooth mobility and displacement. Radiographically, there is a well-defined unilocular radiolucent image surrounding the apex of a tooth. As for treatment, tooth extraction and nonsurgical endodontic treatment are the most executed procedures; in extensive lesions, conservative endodontic treatment followed by biopsy and decompression have been successfully performed. The authors report a case of radicular cyst of great proportions in a patient aged 18 years. After diagnosis was confirmed by clinical and radiographic examinations, treatment plan consisted of surgical and nonsurgical endodontic treatment of the left maxillary canine. No signs of recurrence were found during follow-up. The present work aims at reporting a case of a large cystic lesion of 3.4 cm in the anterior maxilla in a young patient, and it is made a brief review of the literature regarding such pathological entity. DESCRIPTORS: Radicular Cyst. Decompression. Surgery, Oral.