Odontogenic keratocysts (OKCs) are benign cysts arising from the dental lamina and its remnants. They are most commonly located in the posterior body and the ramus of the mandible. The diagnosis of peripheral OKCs (other than intraosseous) are extremely rare and the current literature is limited. The most common location is the gingiva, but mucosal, epidermal, and even intramuscular sites have also been described. Currently 15 cases have been described. The origin and nature of peripheral OKC still remains controversial. The differential diagnosis includes gingival cyst, mucoceles and epidermoid cyst. Soft tissue OKCs have a lower rate of recurrences; 12,5% vs. 62% in intraosseus OKCs. We report a case of a 58-year-old woman with a peripheral OKC, located in the left masticatory space. We performed a review of the existing literature on peripheral odontogenic keratocysts. Key words:Odontogenic keratocysts (OKCs), peripheral keratocyst, mandibular cyst.