Odontogenic keratocyst is a development odontogenic cyst with aggressive biological behavior characterized by high rates of recurrence. A 40-year-old male patient complained of asymmetry in the right hemiface. Intraoral examination revealed expansion of the alveolar ridge, firm on palpation, and no changes in the color of oral mucosa. Panoramic radiography showed a large radiolucent multilocular lesion involving the entire mandibular ramus up to tooth 46. The diagnostic hypotheses were ameloblastoma and odontogenic keratocyst. An incisional biopsy was performed, and the histopathologic examination revealed a cystic lesion characterized by the presence of a pathologic cavity lined by parakeratinized stratified squamous epithelium, showing a corrugated surface and palisade hyperchromatic basal layer cells with the surrounding capsule consisted of fibrous connective tissue. Histopathologic diagnosis was odontogenic keratocyst and the patient was referred for surgical treatment.