One hundred twenty-two patients with spontaneous angina pectoris (SAP) were randomly divided into treated group (82 cases) and control group (40 cases), and treated with Wenxin decoction and isosorbide dinitrate respectively. Results showed that in treated group the total effective rate of SAP was 95.12% and that of electrocardiographic findings were 74.39%. These results were all superior to those of control group (P < 0.01). Moreover, results of extracorporeal thrombosis test showed after Wenxin decoction treatment, the length of thrombus decreased from 23.56 +/- 5.47 mm to 20.04 +/- 5.17 mm, the wet weight of it decreased from 92.65 +/- 18.45 mg to 76.94 +/- 15.08 mg and the dry weight from 21.76 +/- 7.30 mg to 16.90 +/- 5.35 mg. The submaximal exercise test revealed an increase of exercise time from 474.66 +/- 96.33 seconds to 548.83 +/- 99.93 seconds, increase of acting quantity from 104.16 +/- 19.65 W to 123.61 +/- 24.96 W and a decrease of ST segment depression from 0.183 +/- 0.041 mV to 0.139 +/- 0.038 mV. These results suggested that Wenxin decoction is valuable in treating SAP.