BACKGROUND: It has been reported that early prescription of statin might enhance the vascular protection in acute atherothrombosis by its various mechanisms. However, until now, there has been little information about the serial changes of high sensitive C-reactive protein (hs-CRP), one of the notable inflammatory markers in atherothrombosis, by early prescription of statin in acute ischemic stroke. METHODS: We retrospectively collected one hundred eighteen (118) patients with acute ischemic stroke who had conformed to the Atherosclerotic Stroke Mechanism Algorithm (ASMA), one of the guidelines for statin, and evaluated the effects of Atorvastatin 20 mg on the changes of hs-CRP levels and clinical severity at 7 days and 30 days after ischemic events. RESULTS: Among the 118 patients who should have been prescribed statin on the ASMA guideline, sixty-three patients (53.4%) used the statin (Atorvastatin 20 mg) within 48 hrs after admission. Serum concentration of hs-CRP levels was decreased from admission to 30 days later in both statin and non-statin users. Particularly, its extent was significant (0.39+/-0.74 vs 0.75+/-0.98 mg%, p=0.042) after 30 days of ischemic events in statin users. Statin users had lower mortality and vascular recurrence (p=0.083) and fewer bad prognosis rates (27.7% vs. 34.5%) compared to non-statin users over 30 dyas after ischemic events, although there was no statistical significance. CONCLUSIONS: These results suggest that early prescription of statin (Atorvastatin 20 mg) might regulate the inflammatory activity over 30 days after acute ischemic stroke.