Background and Purpose : Hypertension is one of the modifiable risk factors for stroke. Lowering blood pressure is a primary or secondary preventative measure for stroke. This study aims to assess the efficacy of Chunghyul-dan(Qingxue-dan) in stage 1 hypertensive patients who have suffered a stroke by 24 hour ambulatory blood pressure monitoring(24ABPM). Subjects& Methods : We enrolled 40 hospitalized stroke patients with stage 1 hypertension and divided them into 2 groups by stratified randomization; group A took 1200mg of Chunghyul-dan(Qingxue-dan) at 8:00 a.m. for two weeks without changing herbal medicine, and group B was the control group. 28 patients were included in the final analysis(15 in group A. 13 in group B). Blood pressure is monitored from 8:00 am to 7:30 am every 30 minutes for 24 hours. Blood pressure was monitored two times at baseline and again two weeks later. We used 3 parameters for evaluating the efficacy of Chunghyul-dan(Qingxue-dan); The first parameter is change from baseline to two weeks later in blood pressure and pulse rate. The second parameter is the trough/peak ratio(TPR) and smoothness index(SI). The third parameter is antihypertensive rate by antihypertensive efficacy guideline. Results : There is no significant difference in the baseline assessment hetween the two groups. Systolic blood pressure $(141.37{pm}8.96;mmHg;vs;132.28{pm}9.46;mmHg)$ decreased after two weeks of 1200mg(P=0.03) intake of Chunghyul-dan(Qingxue-dan). Systolic TPR and SI was 0.87 and 1.04 in group A. Antihypertensive rate was higher in group A. Conclusion: These results suggest that 1200mg doses of Clunghyul-dan(Qingxue-dan) is an effective antihypertensive agent on stage 1 hypertension patients who have suffered a stroke.