Objective To investigate the changes of plasma decorin in patients with acute ischemic stroke and its clinical significance. Methods The plasma levels of decorin were assessed in 102 patients with acute ischemic stroke (< 7 days) and 120 control subjects using ELISA. Then we evaluated the relationship between decorin level and the TOAST subtypes of stroke, so as to analyze the role of decorin level in diagnosis and treatment of acute ischemic stroke. Results Compared with the control group, the decorin level was significantly decreased in acute ischemic stroke group (P<0.001), and that in the large-artery atherosclerosis group was lower than those in other groups of the same level. According to the receiver operating characteristic curve, decorin level was a diagnostie marker for acute ischemic stroke (P<0.001). Decorin levels <8 500 pg/mL yielded a sensitivity of 79.4% and a specificity of 62.8% for diagnosis of acute ischemic stroke. Logistic regression indicated that decorin level <8 500 pg/ml was an independent risk factor of acute ischemic stroke (OR=4.8; 95%CI: 2.1-11.1; P<0.001). ConclusionDecorin level is significantly decreased in patients following acute ischemic stroke. The changes of decorin level can contribute to the diagnosis and treatment of acute ischemic stroke.