Twenty-four reports describing 39 cases of primary intraosseous carcinoma (PIOC) were reviewed and the clinicopathologic features were summarized. The mean age of the patients at the time of diagnosis was 51.0 years, and the male: female ratio was 2:3. The posterior mandible was the predominant site; in no patient was a lesion observed in the posterior maxilla. Twenty-five of 31 patients (80.6%) showed swelling of the oral mucosa. However, ulcer formation was observed in only 3 of 36 patients. Pain, sensory disturbances, and metastasis to regional lymph nodes were observed in 25 of 34 patients (73.5%), 9 of 15 patients (60%), and 13 of 33 patients (39.4%), respectively. Radiographically, most lesions produced bone resorption with ill-defined margins (51.6%) or with well-defined margins (19.4%). The diagnostic criteria proposed for PIOC are absence of ulcer formation, except when caused by other factors; histologic evidence of squamous cell carcinoma without a cystic component or other odontogenic tumor cells; and absence of another primary tumor on chest radiographs obtained at the time of diagnosis and during a follow-up period of more than 6 months.