Odontogenic keratocysts are developmental odontogenic cysts which derived from rests of dental laminas and often found in posterior area of mandible. Because this lesion has tendency of frequent recurrence, treatment of choice is often radical removal of the lesion. Sometimes in case of large cysts, however, conservative therapy like marsupialization is often selected in treatment plan. A 39-years old woman referred to our department for evaluation of large radiolucent lesion that occupies the areas from mandible angle to upper part of ramus and condyle. In cytology, the lesion was identified as odontogenic keratocyst. Marsupialization was our treatment of choice, and the result was so favorable. 2 years later, there was small radiolucent lesion on upper part of mandibular ramus on panoramic view. It was suspected as recurred lesion, and excisional biopsy was done. On biopsy result, it was not a cystic lesion but fibrosis.