Statement of Problem: Odontogenic keratocyst is a developmental odontogenic cyst which arises from dental lamina. One of the important features of odontogenic keratocyst is strong tendency to recurrence.

Purpose: The purpose of this study was the statistical evaluation of age and gender of patient as well as area of involvement in odontogenic keratocysts in the oral and maxillofacial pathology department of dental faculty of Tehran University of Medical Sciences from 1971-2002. Materials and Methods: This study was a cross sectional, descriptive one. Medical records were reviewed and variables such as age, gender and site of involvement were recorded. The data were analyzed with SPSS software.

Results: The relative frequency of odontogenic keratocyst was 36%. 66% of cysts were in men and 34% in women. 68% of lesions affected the lower jaw and 32% the upper jaw. Regarding the site of involvement, 48% of lesions involved the molar region of mandible and 42%, the anterior part of maxilla. The occurrence of keratocysts was higher in this sites. Most of the cases were diagnosed in the third decade.

Conclusion: Based on the findings of this study, odontogenic keratocyst was more prevalent in men, mandible and the third decade. The posterior part of mandible and anterior region of maxilla were involved most frequently.