Abstract Endothelial progenitor cells (EPCs) home to sites of tissue injury and differentiate into mature endothelial cells. Their transfer feasibility has been proven in models of hindlimb ischemia and myocardial infarction. We investigated, the effect of delivery of spleen-derived EPC in a rat model of inflammatory-mediated myocardial damage. Male Lewis rats ( N = 25) were immunized against myosin. Healthy donor Lewis rats were sacrificed, their spleens harvested, separated on Ficoll gradient centrifugation, and grown on fibronectin coated plates with endothelial cell medium for 5 days. Ten days after myosin immunization, spleen cell derived EPC were collected, and labeled 2 × 10 7 cells per rat were injected into the femoral vein of diseased rats. Cell transplantation was repeated twice, 2 and 4 weeks after initial cell transfer. Rats with inflammatory-mediated cardiomyopathy exhibited a significant mobilization of EPC from the bone marrow to the periphery and their ability to adhere to fibronectin, mature endothelial cells and cultured cardiomyocytes was significantly reduced when compared to healthy rats. Transfer of EPC resulted in a functional improvement in cardiac performance evident by higher fractional shortening by echocardiography (a 15% increase). Histological studies exhibited reduced scar tissue and thickened ventricular walls in rats receiving EPC as compared with untreated animals. EPC transfer is effective in attenuating myocardial damage in a model of non-ischemic dilated cardiomyopathy.