AIM: To study the protective effects of n on -mitogenic human fibroblast growth factor (nm-haFGF) on cardiomyocytes injured b y reactive oxygen free radicals. METHODS: The cardiomyocytes were isolated from neonatal SD mouse by trypsin digestion. The cardiomyocytes injury model was established by expos ing the cells to hydrogen peroxide (H 2O 2), and the injury status in cardiomy ocytes were evaluated by examining the cellular viability, measuring cell apopto sis and observing the change of cellular morphology. nm-haFGF was added to the c ulture medium, and the changes of cellular viability, superoxide dismutase (SOD) , malondialdehyde (MDA) and celluar apoptosis were observed. RESULTS: A dose-dependence relation between the concentration of H 2O 2 and the cardiomyocytes injury was observed. 10-80 ?g/L nm-haFGF dose -dependently increased cardiomyocyte viability and the general SOD activity, as well as decreased the content of MDA and the quantity of cardiomyocyte apoptosis . CONCLUSION: The higher the concentration of H 2O 2, the mor e serious the cardiomyocyte injury. nm-haFGF may have a good protective effects on cardiomyocytes treated with H 2O 2.