Aim To explore relationship between the serum neopterin level and atherosclerosis thrombotic cerebral infarction(ATCI). Methods The neopterin of peripheral vein were measured in 50 cases of acute stage of ATCI and 50 cases of healthy controls. Results The levels of neopterin of peripheral vein in acute stage of ATCI group were significantly higher than those in healthy controls(5.07±1.70 μg/L vs 2.04±0.21 μg/L,p<0.05). Conclusion The levels of neopterin were significantly elevated in patients with ATCI,immune activition probably participated in course of pathophysiology of acute stage of ATCI,and neopterin was an important mark of the activity of ATCI.