Objective:To investigate the effect of ventricular remodeling and AngⅡafter using recombinant human midkine(MDK) in early myocardial infarction in rats.Methods:Acute myocardial infarction model was made by ligating the anterior descending coronary artery. Thirty two rats were randomly divided into three groups:sham operation group (Sham n=15),acute myocardial infarction group (MI n=15) and treated group (MI+MDK n=15). In MI+MDK group, each rat was immediately treated by injecting doses of lug/200g recombinant human MDK into the border zone myocardium at five sites after the ligation succeed. After 4 weeks, all rats were detected there hemodynamics, serum AngⅡ, vascular density, collagen volume and pathological analysis of cardiac specimens.Results:Compared with sham-operated rats, LVW, LVW/BW. LVD and myocardial angiotensinⅡlevel were significantly increased (all P<0.01), while the LV systolic pressure(LVSP),the maximum rising and dropping rates of LV pressure(±dp/dt) in AMI control group were significantly reduced (all P<0.01).In compared with AMI control group, LVW/ BWand LVD in MK treatment group were significantly decreased(P<0.05 or P<0.01), LVW/ BW, MI size,LVD and myocardial angiotensin II in MK treated AMI rats were significantly lower (P<0.05 or P<0.01).Pathology specimens analysis:Compared with the MI group, collagen volume fraction in MI+MDK group was increased significantly in infarct area, while in non-infarct area was reduced significantly(P<0.01); inflammatory cell infiltration.infarct size, myocardial hypertrophy, ventricular weight in MI+MDK group were significantly reduced(P<0.01). Conclusion:This study shows that in acute myocardial infarction in rat heart, the early application of MDK may play angiogenesis and collagen stimulating role.And it can play an important role in delaying ventricular remodeling after acute myocardial infarction.