Background:Significant increase in cell proliferation and vascularity occurs during the transition from normal oral mucosa through differing degrees of dysplasia to oral squamous cell carcinoma (OSCC).Aims:To evaluate the cell proliferation and vascularity in potentially malignant disorders and OSCC.Settings and Design:Proliferating cell nuclear antigen (PCNA), vascular endothelial growth factor (VEGF) and CD34 were quantified immunohistochemically (IHC) using anti-PCNA, anti-VEGF and anti-CD34 antibody.Materials and Methods:A total of 60 archival specimens included 10 oral lichen planus, 10 oral leukoplakia, 10 oral submucous fibrosis and 30 OSCC (well differentiated, moderately differentiated and poorly differentiated), and also, 10 normal oral mucosa as control group were taken. PCNA, VEGF and CD34 expression was assessed in relation to the localization and area of IHC-stained cells.Statistical Analysis:One-way analysis of variance test and post hoc least significant difference test were assessed for statistical significance.Results:Cell proliferation and vascularity appeared to increase gradually with disease progression.Conclusion:Upregulation of cell proliferation and vascularity indicates their possible role in malignant transformation of potentially malignant disorders.