We investigated 52 cases of 42 patients who were diagnosed as odontogenic keratocyst in the department of Oral and maxillofacial Surgery of Kyungpook National University from 2006 to 2008, and following results were obtained. 1. Among 52 cases of OKCs, all cases were parakeratinzied. 2. Among 52 cases of OKCs, 42 cases were type I, 9 cases were type II and 1 case was type V. 3. Among 52 cases of OKCs, there were bud-like proliferation of basal cell layer on connective tissue area on 10 cases, satellite cysts on overlying oral mucosa or connective tissue area on 6 cases and rests of epithelium on connective tissue area on 6 cases. 4. Among 52 cases of OKCs, there were focal inflammation on the epithelium of the OKCs on 6 cases and diffuse inflammation on 8 cases. 5. Among 52 cases of OKCs, cytokeratin-10 was expressioned on superficial and intermediate layer on all cases. Accordingly, the presence or absence of cytokeration-10 on the epithelium of the cyst will be good differential diagnosis of between OKC and dentigerous cyst.