[Objective]To observe the changes of level of tumor necrosis factor super-family (TNFSF) member LIGHT in the peripheral blood of patients with multiple sclerosis (MS) and explore the related mechanism.[Methods]Twenty-five patients with MS,admitted to our hospital from November 2009 to May 2011,were chosen in our study;another 22 patients with cerebral infarction (CI) and 27 healthy controls (HC) were chosen.By the use of ELISA and real-time PCR,the plasma LIGHT level and LIGHT mRNA expression in the peripheral blood mononuclear cells (PBMC) were measured;the expanded disability status scale (EDSS) was adopted to reflect the disease severity of MS patients at the time of blood sampling.[Results] MS group had a significantly increased level of plasma LIGHT (133.2 pg/mL) and mRNA expression level of PBMC LIGHT (0.75 relative unit) as compared with HC group (41.2 pg/mL and 0.3) and CI group (79.55 pg/rnL and 0.44,P＜0.05).[Conclusion] There is a dysregulated peripheral LIGHT expression in MS patients;and its abnormal immune response may play an important and complex role in MS-related CNS inflammatory process.