Objective:To observe the effect of Wutou Chishizhi pill on myocardial injury and blood viscosity in rats with chest Bi caused by cold and pituitrin. Methods: The chest Bi rat model was induced by rat swimming in ice water for 14 days and pituitrin 20U/kg injected intraperitoneally at the last day.After pituitrin injected, ECG Ⅱ was traced for 30 minutes.24 hours later, blood were collected via carotid artery for assaying the plasma CK、LDH activity and blood viscosity, and the cardiac ventricle were dissected and examined with light microscope. Results:CDDPG、YPMG and YPHG can lower the elevation of J point of ECGⅡ( P<0.01),and obviously decrease the activities of CK、LDH and blood viscosity(P<0.05),and lessen the myocardial injury. Conclusion:Wutou Chishizhi pill has a protective effect on myocardial injury in rats with chest Bi caused by cold and pituitrin. It can lower blood viscosity, and thus, may enhance the cardiac blood supply, which may explain how Yutouchishizhi pill works.