The Odontogenic keratocyst (OKC) is a developmental, non – inflammatory chronic cystic lesion, on radiograph it may be unilocular or multi locular OKC is a cyst of odontogenic origin, usually asymptomatic with an aggressive clinical behavior including a high recurrence rate and tendency to invade bone and adjacent soft tissues. Diagnosis is based on the clinical history, clinical appearance, and radiographs and histology. A case of odontogenic keratocyst involving the ramus of the mandible is presented in this article emphasizing on the characteristics and various features of OKC.