BACKGROUND Oral leukoplakia, oral submucous fibrosis, and oral lichen planus are the precancerous or potentially malignant lesions and conditions whereas oral squamous cell carcinoma (OSCC) is a cancerous or malignant lesion of the oral cavity. They have characteristic clinical and histopathological features. These diseases not only originate from epithelium but also associated with chronic inflammation juxta-epithellialy. Mast cells present in the connective tissue stroma and release pro-inflammatory and mitogenic cytokines. These functions of mast cells contribute and enhance the pathogenesis translation of diseases. OBJECTIVE The study was done to histologically evaluate the number of mast cells in oral epithelial dysplasia and OSCC and compare it with normal oral mucosa (NOM). METHODS Forty-five cases each of oral dysplasia, OSCC and ten cases of NOM were studied for mast cell number using toluidine blue. RESULTS There was a highly significant increase of mast cells in oral epithelial dysplasia on comparison with OSCC whereas there was only a significant increase in mast cells in OSCC on comparison with NOM. CONCLUSIONS The literature has proven that mast cells can be an indicator of increased angiogenesis and hence can help in the prediction of carcinogenesis, its progression, and also the prognosis of the malignant lesions.