Objective:To investigate the protective effects and possible mechanisms of cortex phellodendri water extract and etha -nol extract on the myocardial injury induced by pituitrin and isoproterenol hydrochloride in rats .Methods:SD rats as the experimental animals were randomly divided into the normal control group , model group , compound Danshen tablets group , phellodendron water ex-tract group and phellodendron ethanol extract group .Pituitrin and isopropyl adrenaline hydrochloride were used to establish the myocar-dial injury model in rats.The serum CK, LDH activity, myocardial tissue SOD activity and MDA content were detected and compared . Results:Compared with those in the normal control group , the serum LDH activity , CK activity and MDA content were significantly in-creased , and the SOD activity in cardiac muscle and myocardial tissue was significantly decreased in the pituitrin -established myocardi-al injury model group (P<0.01).In the isopropyl adrenaline hydrochloride-established myocardial injury model group , the MDA con-tent in myocardial tissue was obviously increased , and the SOD activity in myocardial tissue was decreased obviously (P<0.01).The serum LDH activity, CK activity and MDA content were significantly decreased , and the SOD activity in cardiac muscle and myocardial tissue was increased significantly in all drug-taken groups when compared with those in the pituitrin-established myocardial injury model group, and the differences were statistically significant (P<0.05 or P<0.01).The MDA content in myocardial tissue was significant-ly reduced , and the SOD activity was increased significantly in all drug-taken groups when compared with those in the isopropyl adrena-line hydrochloride-established myocardial injury model group , and the differences were statistically significant (P<0.05 or P<0.01). Conclusion:Cortex phellodendri extract has certain protective effect on myocardial injury induced by pituitrin and isopropyl adrenaline hydrochloride in rats .