Abstract: Objective：By studying the expression of stromal interaction molecule 1 (STIM1) in lesions of oral lichen planus (OLP) to explore the pathogenesis of OLP. Methods：The mRNA expression level of STIM1 in 37 OLP and 17 healthy adults’ peripheral blood lymphocytes was determined by real-time fluorescence quantitative PCR．The protein expression level of STIM1 from the same populations was determined by Western blot. Results：Increased STIM1 mRNA expression was found in OLP to be higher than that in healthy populations (P<0.01); Expression of STIM1 protein was significantly higher in OLP than in healthy controls (P<0.01). Differences between two groups of OLP patients were not statistically significant (P＞0.05). Conclusions：Increased expressions of STIM1 in OLP peripheral blood lymphocytes, which can regulate lymphocyte immune response，may be involved in the pathogenesis of OLP and play an important role in the process of repeated episodes of OLP.