Abstract: OBJECTIVE To evaluate the protective effects of salvianolic acid B magnesium (Sal-B) on the myocardial injury after acute myocardial infarction and reperfusion in rabbits. METHODS Forty New Zealand rabbits were divided randomly into four groups(n=10):sham operation group, myocardial ischemia/reperfusion(MI/R) group, Sal-B 20 mg·kg^-1 group (reperfusion with the treatment of low dose group), Sal-B 60 mg·kg^-1 group (reperfusion with the treatment of high dose group). The rabbits in the sham operation group were only opened chest without ligation, the others were subjected to 90 min of coronary occlusion followed by reperfusion for 120 min. The serum levels of CK-MB, cTnI were respectively detected in the former 5 min ligation and 90 min ligation, 120 min reperfusion. And to evaluate the area range of no-reflow, infracted area and risk area of the heart. RESULTS After 90 min ligation, serum contents of CK-MB, cTnI were no significant among MI/R group, Sal-B 20 mg·kg^-1, Sal-B 60 mg·kg^-1 group. Serum of CK-MB, cTnI contents in Sal-B 60 mg·kg^-1 group was lower than that in MI/R group and Sal-B 20 mg·kg^-1 group after 120 min of reperfusion (P<0.05). The ligation area(LA) measured by pathological evaluation were no significant difference in all groups. Compared with the MI/R group and Sal-B 20 mg·kg^-1 group, the degree of reduction in infarct size and morphological injury of myocardium were more significantly in the Sal-B 60 mg·kg^-1 group (P<0.05). The area of myocardial infarction in the MI/R group and Sal-B 20 mg·kg^-1 group were similar. CONCLUSION Sal-B 60 mg·kg^-1 can reduce myocardial cell structure damage, decrease no-reflow area and myocardial infarction size in experimental acute myocardial ischemial-reperfusion.