30 cases of chronic cor pulmonale with acute exacerbation were treated with Fei Xin Ling Syrup compared with 30 similar cases treated with Western modern drugs as controls. The Chinese herbal drug modality was found to be superior to the administration of modern drugs in the control group in overall therapeutic effects, with regard to the symptoms of coughing, tachypnea, phlegm production, edema, and the prevention of heart and respiratory failure. Rheological studies in part of the patients also indicated that the Chinese herbal prescription improved the blood circulation.