Abstract: Paeonl60 mg·kg^-1ip,was given to rats for 15 days.On the 16th day myocar-dial ischemia reperfusion injury was produced in the rat heart by occlusion of the left coronary arteryand the release of the occlusion. The results showed that paeonol signi ficantly improved myocardialSOD activity(5.8±0.6.mg-1 compared with reperfusion control 3.4±0.9,P<0. 01),reducedthe MDA content(11.4±1.7 nmol· mg^-1 versus 17±1.3,P<0. 01 ) and cardiac CPK release(1523±478.5U·L^-1versus2355±626.5,P <0.01).The myocardial ultrastructure was alsoprotected keeping them from the oxygen free radical damage.It appears that paeonol is an efficientprotective agent against ischemia reperfusion damage in the rat heart.