Abstract Increased levels of asymmetric dimethylarginine (ADMA) have been observed in patients with acute ischemic stroke. We aimed to investigate the correlation between ADMA and ischemic stroke, and evaluate the effect of the supplementation of folic acid and vitamin B12 on concentrations of ADMA. Patients were randomized into intervention and non-intervention group within 3days after symptom onset. Intervention group patients were treated with folic acid (5mg daily) and vitamin B12 (500ug twice daily) for 12weeks. ADMA and homocysteine (Hcy) concentrations were measured before treatment (baseline) and 2 and 12weeks after treatment. The laboratory measures were also collected from healthy controls. Eighty five subjects were enrolled in this study, from whom 72 with complete baseline and follow-up laboratory data were included in the present analysis. Thirty four patients were assigned to the intervention group and 38 patients to the non-intervention group. Sixty people were enrolled as healthy controls. Levels of ADMA and Hcy were raised (p<0.05) in patients with acute ischemic stroke. With supplementation of both folic acid and vitamin B12, the levels of ADMA and Hcy decreased significantly at 2 and 12weeks (p<0.05). The present study reconfirmed that ADMA can be regarded as a risk biomarker for acute ischemic stroke. We observed that with supplementation of folic acid and vitamin B12 levels of ADMA were decreased in patients with acute ischemic stroke.