We have previously shown that VEGF165 gene delivery into ischemic skeletal muscle exerts not only proangiogenic, but also remarkable antiapoptotic and proregenerative activity. The aim of this study was to determine whether recombinant adeno-associated virus (rAAV)-mediated gene delivery of VEGF165 into cardiac muscle, during acute myocardial infarction, exerts a protective effect to promote long-term functional recovery. Acute infarction of the anterior LV wall was induced in 12 chronically instrumented dogs by permanent occlusion of the LAD coronary artery. Four hours after occlusion, rAAV-VEGF165 or rAAV-LacZ (n=6 each; 5×10¹² viral particles per animal) was directly injected with an echo-guided needle into the dysfunctional cardiac wall. LV and arterial pressure, dP/dt_max, and ejection fraction were not significantly different between the two groups over time. In contrast, in the infarcted region, at four weeks after infarction, fractional shortening was 75±18% and −3±15% of baseline and length-pressure area was 54±15% and 0.8±15% of baseline in VEGF165 versus LacZ, respectively (P<0.05). Histological analysis of the border regions showed a marked increase in the number of α-SMA-positive arterioles (68±2.8 versus 100±3.8 vessels per microscopic field in LacZ and VEGF165 group, respectively; P<0.05). In both groups, the receptor VEGFR-2 was diffusely expressed on the surviving cardiomyocytes and, consistently, myocardial viability was significantly improved in the VEGF165-treated group, with several troponin T-expressing cardiomyocytes displaying nuclear positivity for the proliferation marker PCNA. Altogether, our results indicate that VEGF165 gene delivery exerts a marked beneficial action by enhancing both arteriologenesis and cardiomyocyte viability in infarcted myocardium.