The combination of high p53 values with high Ki67/p53 ratio was observed in 93% (50 out of 54) of OSCC and in 81% (22 out of 27) of epithelial dysplasias, of which 89% (17 out of 19) from non-tumoral areas adjacent to OSCC, and in 50% (16 out of 32) of epithelial hyperplasias, while it was never observed in any sample from normal mucosa. This evidence concerns the gene TP53 and intraepithelial neoplasia.