To identify the predictors of disease, more knowledge about their genetic profiles is necessary. This study aimed to characterize alteration in the DNA copy number of PA and CPA. Objective: Leukoplakia is an oral premalignant white lesion. Although its etiology may vary, smoking has been implicated as a possible risk factor. The p27 protein has been shown to inhibit kinases, and it is known that its expression is decreased during carcinogenesis. The reduced expression of p27 has been correlated with poor prognosis in carcinoma. In this study a role for the smoking habit in the expression of this protein was investigated.