Objective: the role of p53 expression in odontogenic lesions has not been fully determined, but has been associated with cell proliferation. The purpose of this study was to analyze p53 and proliferating cell nuclear antigen (PCNA) expression in 4 different odontogenic lesions. Design: expression of p53 and PCNA was analyzed in radicular and dentigerous cysts, odontogenic keratocysts, and calcifying odontogenic cysts (Gorlin cysts) using monoclonal antibodies for detection of p53 and PCNA. Results: PCNA expression was significantly greater in the basal layer of radicular cysts and in the suprabasal layer of odontogenic keratocysts; the percentage of p53 positive cells was significantly greater in the suprabasal layer of odontogenic keratocysts. Conclusions: The patterns of p53 and PCNA expression in dentigerous and radicular cysts were similar although the two lesions are of different origin. In odontogenic keratocysts and Gorlin cysts, results indicate a different pattern of tumor growth.