Oral epithelial dysplasia is a precancerous change develops in the oral mucosa, and leukoplakia is the most common precancerous lesions in oral mucosa. The epithelial-mesenchymal transition (EMT) is considered the mechanism through which the oral leukoplakia becomes malignant, and it's also responsible for the invasion and metastasis of cancers. This study investigates the expression of β-catenin in epithelialmesenchymal transition detected by immunohistochemical staining in the different grades of oral epithelial dysplasia. The sample consisted of 45 formalin-fixed, paraffin-embedded specimens of oral leukoplakia with different grades of oral epithelial dysplasia; specimenswere immunohistochemically stained with β-catenin antibody. The control group was consisted of biopsies from the normal oral epithelia. The EMT rates are associated with the severity of the oral epithelial dysplasia.That means, the epithelial-mesenchymal transition marker β-catenin could be used to evaluate the potentiality of malignant transformation in the precancerous lesions.