Description: Male patient, 48 years old, a smoker, without any general health problems, first came to the clinic in january 2016 reporting pain in the 4th quadrant. Clinically, theeth 44 and 45 presented extensive cavities and coronary destruction. The patient said that he had been diagnosed with a periapical lesion a year ago and had done some antibiotic therapy due to pain and suppuration. The radiographic exam showed a radiolucent unilocular lesion with radiopaque contour associated with teeth 44 and 45, both with endodontic treatment. In March 2016, teeth 44 and 45 were removed and decompression of the lesion trough the placing of a drain was accomplished. After 8 months, the enucleation of the cystic lesion was performed. The histopathological exam confirmed the provisional diagnosis of radicular/inflammatory cyst. Discussion: The radicular cysts are the most frequent cystic lesion in the oral cavity. Their treatment depends on their dimensions and their proximity to noble structures. In this case report, the lesion showed significant expansion and close relation with the alveolar nerve. Therefore, before the enucleation was done, it was decided to perform decompression by placement of a drain. This approach made it possible to decrease the lesion's volume and to minimize the risk of damaging the vascular and nervous structures. Conclusion: Periapical lesions can be asymptomatic for long periods of time and they can grow up to very significant dimensions. This leads to more complex treatments that may need to be done in various stages. Keywords: radicular cyst, enucleation, decompression, oral pathology