Oral lichen planus (OLP) is a common lesion of the oral mucosa that can progress to cancer. E-cadherin is involved in intercellular adherence and the pathogenesis, development and metastasis of tumors, and is considered to be an important indicator of tumor progression and prognosis. The aim of this study was to investigate the expression of E-cadherin in OLP in order to elucidate its role in the pathogenesis and malignant transformation of OLP and provide evidence to support the early diagnosis and treatment of OLP with malignant potential. OLP specimens (n=52) and samples of normal oral mucosa (n=41) as the control were collected. Immunohistochemical staining was conducted to reveal the expression of E-cadherin in the OLP samples and normal oral mucosa. It was observed that 25 of the 52 OLP specimens exhibited normal positive expression of E-cadherin and 27 exhibited abnormal positive expression, corresponding to an abnormal positive rate of 51.92%. In the normal oral mucosa group, 39 of the 41 cases exhibited normal positive expression and 2 exhibited abnormal positive expression. The abnormal positive rate in the normal oral mucosa was 4.88%, which was significantly lower than that in the OLP group. The significantly elevated rate of abnormal positive expression of E-cadherin in the OLP group indicates the involvement of E-cadherin in the malignant transformation of OLP and supports the malignant potential of OLP.