In this study, we included 26 cases diagnosed as squamous intraepithelial lesions, which were examined histopathologically, and in terms of p16, E-cadherin and Ki67 immunoexpression. In low-grade lesions, p16 expression was limited to one third below the epithelium, E-cadherin has a membranous pattern and Ki67 proliferation index had low values. In high-grade lesions, the p16 diffuse stain was present in two thirds or all epithelium layers, E-cadherin expression became aberrant, with membranous and cytoplasmic pattern and Ki67 proliferation index was high. These biomarkers have proven useful to accurately assess the extent of lesions and to identify lesions with high risk of progression.