Orthokeratinized odontogenic cyst (OOC) was initially defined as the uncommon orthokeratinized type of odontogenic keratocyst (OKC) by the World Health Organization (WHO). Several studies have shown that OOC has different clinicopathologic aspects when compared with other developmental odontogenic cysts, especially OKC. So OOC now emerges to be a distinct entity, according to the 4th edition of the WHO Classification of Head and Neck Tumors which was published in January 2017. Clinically, it usually occurs as a single cyst with a unilocular radiographic appearance in posterior mandible with a predilection in males and mostly is seen between the third and fourth decades. In this case we present an OOC arise as a multilocular lesion causes thinning and expansion of the buccal cortical plate treated by enucleation and curettage.