Objective?To understand the possible role of signal transducer and activator of transcription 1 (STAT1) and interferon-γ (IFN-γ) in the generation of local lesions of oral lichen planus (OLP). Methods?Formalin-fixed, paraffin-embedded tissues of 10 cases of normal oral epithelium and 48 cases of OLP were investigated for STAT1 and IFN-γ proteins by using immunohistochemistry SABC method. The correlation between the expression of STAT1 and IFN-γ proteins and the clinical and pathological characteristics in OLP were statistically analyzed. Results ① STAT1 and IFN-γ were over expressed compared with healthy oral mucosa (Pχ2=5.042,?Pr=0.324, Pχ2=5.077, Pr=-0.388, P