Objective To study the level and clinical significance of serum interleukin-18(IL-18)in patients with acute cerebral infarction.Methods The level of serum IL-18 in patient with acute cerebral infarction(n=90)and normal controls group(n=45)were detected by enzyme linked immunosorbent assay.Results The level of serum IL-18 in large,medium and small lesion group were(288.4±59.3);(237.5±58.0);(186.9±50.6)ng/L respeetlvely,which were significantly higher than those in normal control group.The level of serum IL-18 in control group was(147.2±42.8)ng/L(P＜0.05).large lesion group was significantly higher than that in medium and small lesion group(P＜0.05).medium lesion grouP was significantly higher than that in small lesion group(P＜0.05).The levd of serum IL-18 in heavy,medium and light group were(284.9±57.3);(233.4±55.9);(184.5±48.3)ng/L respectively,which were significantly higher than those in normal control group(P＜0.05);heavy group was slgnificantly higher than that in medium and light group(P＜0.05),medium group was significantly higher than that in light group(P＜0.05).Conclusion The level of serum IL-18 was related to the severity of cerebral infarction,IL-18 may be involved in the pathogenesis of the hypoxic ischemic brain injury.