Skeletal myoblast transplantation has been applied clinically for severe ischemic cardiomyopathy. Matrix metalloproteinase 1 (MMP-1) reduces fibrosis and prevents the progress of heart failure. We hypothesized that MMP-1 administration to the infarct area enhances the efficacy of skeletal myoblast transplantation. The controlled release of MMP-1 improved cardiac functions of rats with chronic myocardiac infarction with or without transplantation of skeletal myoblasts. Improvement in cardiac function and small fibrotic area inside the infarcted area were observed compared with those of myoblast transplantation. In conclusion, controlled release of MMP-1 was effective in cardioprotection in postmyocardial infarction although the combination with cell transplantation showed the similar effect.