Backgroud: Heat shock proteins (HSPs) provide one kind of defense against stresses such as high temperature, hypoxia/ischemia and oxidative stress in all mammalian cell types. One such protein which is highly induced during the stress response is hsp27, and its expression is correlated with the cellular survival in response to cytotoxic insults. Recent studies have been established that the overexpression of hsp27 protects against cell death triggered by a variety of stimuli including ischemia/reperfusion, hyperthermia, and various cytotoxic agents. Previous findings have suggested that augmentation of the heat shock response by increasing the expression of hsp27 represents a potential therapeutic strategy for the treatment of critically ill patients. In this study, using protein delivery approach, we studied the potential cardiac protective effect of hsp27 as a therapeutic protein Methods and results:We used rat cardiac myoblast H9c2 cells and rat LAD ligation model of focal ischemia. Human hsp27 cDNA was cloned and fused with a gene fragment encoding the basic domain from HIV-1 Tat protein called the protein transduction domain (PTD). Then, the efficiency of transduction of the resulting Tat-hsp27 fusion protein into H9c2 cells was analyzed. The Tat-hsp27 fusion protein was efficiently delivered to H9c2 cells, and its transduction showed cytoprotective effect against the hypoxic stress. Moreover, transduction of Tat-hsp27 also attenuated hypoxia-induced apoptosis, which was accompanied by reduced caspase-3 activity. In addition, intraperitoneal injection of Tat-hsp27 into rat resulted in efficient protein transduction in heart tissues within 2 h, and decreased cardiac infarction, as determined at 7 days after focal ischemia. Conclusion: These experimental findings suggest that the PTD-mediated delivery of therapeutic proteins may represent a novel strategy of protein therapy.