The results showed that at different cut-offs, all the normal cases were under-expressed for nucleic expression of MCM3, while in the case of PMOL (n = 34), including leukoplakia, erythroplakia, lichen planus, submucous fibrosis, and tobacco-induced keratosis, under-expression is observed in most of the cases. This evidence concerns the gene MCM3 and Oral leukoplakia.