Background and Purpose: Studies on the molecular pathways involved in the progression of intracranial large artery atherosclerosis are rare. We aimed to study the relationship between biomarkers and the risk of progression of symptomatic intracranial large artery atherosclerosis. Methods: Of 409 patients in Trial of cilostazol in symptomatic intracranial stenosis-2 (TOSS-2) study, 52 patients showed progression of symptomatic intracranial large artery atherosclerosis on MRA after 7 months. We selected 20 patients with progression and 40 age- and sex- matched control patients. We collected blood sample initially, one month and 7 month after infarction, and multiplex analysis of biomarkers including interleukin-1,2,6,8,10, soluble CD40ligand, TNF alpha, PDGF, soluble ICAM, E-selectin and VCAM , MMP-2,3,9, SOD1,2,3 and adipokines, were performed. Results: Demographic features such as age, sex, hypertension, diabetes and smoking history were not different between both groups. On univariate analysis, 7 month PDGF-AA (3053 ± 2896 pg/ml, vs 1444±1548 pg/ml), PDGF-AB/BB (15304.0±15634 pg/ml vs 5627±8656 pg/ml) level and MPO(25.7±33.9vs 9.9±8.7ng/ml) were higher in progression group. On multivariate analysis using logistic model, 7 month PDGF AA is independent prognostic factor for progression of intracranial large artery atherosclerosis (p=0.012). Conclusion: PDGF-AB/BB level is associated with progression of symptomatic intracranial large artery atherosclerosis.