Objective: To probe into the significance of Nitric Oxide (NO) in ischemic cerebral damage and effect of ligustrazine on it. Methods: The NO contents in cerebrospinal fluid (CSF) and plasma of 20 controls and 62 patients with arteriosclerotic thrombotic cerebral infarction (ligustrazine group and common treatment group) were determined with Griess method before and after treatment. Results:The NO content in CSF before treatment was higher in severe type, it was higher than that in moderate type, and than that in mild type,again higher than that in control group (all P < 0. 05) and was positively correlated with the size of infarction (P < 0. 01 ). There was no significant difference between the plasma NO content of patients and that of control group (P < 0. 05), but there was a trend that plasma NO content decreased as the patient’s condition worsened. After treatment, the curative effect and plasma NO content of ligustrazine group were both markedly higher than those of common treatment group (P < 0. 05, 0. 05 ).There were no significant differences between CSF NO contents of the two groups, respectively, and that of control group (P > 0. 05,0. 05). Conclusion: Excessive NO produced in brain tissue and insufficient plasma NO participate the course of ischemic brain damage.Ligustrazine could increase the contents of plasma NO selectively.Original article on CJIM(Chin) 1998; 18(6). 342 Methods: The NO contents in cerebrospinal fluid (CSF) and plasma of 20 controls and 62 patients with arteriosclerotic thrombotic cerebral infarction (ligustrazine Results: The NO content in CSF before treatment was higher in severe type, it was higher than that in moderate type, and than that in mild type, again higher than that in control group (all P <0.05) and was positively correlated with the size of infarction (P <0.01). There was no significant difference between the plasma NO content of patients and that of control group . 05), but there was a trend that plasma NO content decreased as the patient’s condition worsened. After treatment, the curative effect and plasma NO content of ligustrazine group were both markedly higher than those of common treatme nt group (P <0.05, 0.05). There was no significant differences between CSF NO contents of the two groups, respectively, and that of control group (P> 0.05, 05). Conclusion: Excessive NO produced in brain tissue and insufficient plasma NO participate the course of ischemic brain damage. Ligustrazine could increase the contents of plasma NO selectively. Original article on CJIM (Chin) 1998; 18 (6). 342