Objective: to investigate the immunoexpression of fatty acid synthase(FAS) in oral squamous cell carcinoma (OSCC) and to correlate such expression with the proliferative potential of these tumors.Study Design: Samples of OSCC (30) and of normal oral epithelium(6) were immunohistochemically examined for FAS and Ki-67 expression.FAS expression was correlated to proliferative activity and tohistopathological grade of OSCC.Results: FAS was positive in all cases of OSCC and normal mucosa.FAS expression was significantly higher in well-differentiated than inpoorly differentiated carcinoma. Ki-67 immunopositivity was directlycorrelated to tumors malignancy grade but not with FAS expression.Conclusion: FAS contribute to keratinization process in oral mucosaltissues and may have a role in oral carcinogenesis.