Oral and maxillofacial pathology has paramount importance in connecting basic science and clinical features; progress in this field will improve diagnosis and treatment. Although the prevalence of odontogenic tumors varies in different geographic sites, there are no reports in English on the relative frequency of odontogenic tumors in Iran. In the present 30-year retrospective study, the case records of all patients referred to the Mashhad Faculty of Dentistry during the period 1978-2008 were evaluated. Subsequently, all lesions diagnosed as odontogenic tumors were subjected to microscopic reevaluation. Data regarding sex, gender, location, and histopathology were gathered. Among 8,766 patients, only 165 odontogenic tumors (1.9%) were found, with a mean age of 26.3 years (range 6-81 years). One hundred and fifty-eight tumors were central with high frequency in the posterior region of both jaws especially in the mandible and seven were peripheral tumors, including five in the posterior mandible and two in anterior maxilla. Malignant transformation was seen in three cases as malignant ameloblastoma (1.8%). The most common tumor was ameloblastoma, followed by odontoma, odontogenic myxoma, and adenomatoid odontogenic tumor. Nevertheless, odontogenic tumors occurred more in females in the third decade with affinity for the posterior mandible in this study.