Muscle cell transplantation may delay or prevent cardiac dilation in dilated cardiomyopathy. The present study was designed to compare the effects of the heart function of smooth muscle cell (SMCs) auto-transplantation and heart cell (CMs) allo-transplantation in dilated cardiomyopathic hamsters, and to determine which cells are better for cell transplantation. CMs and SMCs were isolated from BIO 53.58 hamsters, and cultured for transplantation. CMs, SMCs (4 × 10⁶ cells each) or culture medium were transplanted into 17 weeks old BIO 53.58 hamsters to achieve CM transplantation (CMTx), SMC transplantation (SMCTx), and controls (Con) (N=10 each). Cyclosporine (5 mg/Kg) was administered subcutaneously to CMTx. Healthy hamsters (sham, N=6) were used to compare heart functions. Four weeks after transplantation, heart function was evaluated in all groups using a Langendorff perfusion apparatus. Histology demonstrated severe focal myocardial necrosis in the dilated cardiomyopathic hearts. CMTx and SMCTx formed huge muscle tissue in the dilated myocardium. Sham, SMCTx, and CMTx had a better heart function than Con (p < 0.01), and SMCTx had a better peak systolic pressure (p < 0.05) and developed pressure (p < 0.05) than CMTx at any balloon volume. However, sham and SMCTx were not statistically different. SMCTx and CMTx formed muscle tissue and produced better heart function in the cardiomyopathic hearts, and SMCTx showed better systolic and developed pressures than CMTx, even though they were similar in other functions. Significantly, SMCTx had heart functions, which were similar to those of healthy hamster's hearts.