Aims: Prior work suggests that ischemic preconditioning increases the level of CD39 in the heart and contributes to cardiac protection. Therefore, we examined if targeted cardiac expression of CD39 protects against myocardial injury. Main methods: Mice with cardiac-specific expression of human CD39 (alpha MHC/hCD39-Tg) were generated, characterized and subjected to left coronary artery ischemia-reperfusion injury and infarct size at 24 h following injury quantified. Key findings: alpha MHC/hCD39-Tg mice have increased in cardiac ATPase and ADPase activity compared to WT litter mates. The increased activity in alpha MHC/hCD39-mice was inhibited by the CD39 antagonist sodium polyoxotungstate (POM-1). Measurement of basal cardiac function by echocardiography revealed that alpha MHC/hCD39-Tg mice have a lower resting heart rate and increased stroke volume. In response to myocardial ischemia, systolic and diastolic function was better preserved in alpha MHC/hCD39-Tg compared to WT mice. Comparison of Tau also revealed preserved cardiac relaxation during ischemia in alpha MHC/hCD39-Tg hearts. Assessment of myocardial infarct size in response to 60 min of ischemia and 24 h of reperfusion demonstrated a significant reduction in infarct size in alpha MHC/hCD39-Tg hearts. Analysis of isolated cardiomyocytes revealed no basal difference in calcium transients between WT and alpha MHC/hCD39-Tg cardiomyocytes. However, in response to isoproterenol stimulation, there was a trend toward lower calcium transients in alpha MHC/hCD39 cardiomyocytes suggesting less calcium accumulation in response to metabolic stress. Significance: Cardiac-specific expression of CD39 reduces myocardial dysfunction and infarct size following ischemia-reperfusion injury. Increasing nucleotidase expression in the heart may be a novel approach to protect the heart from ischemic injury. (C) 2016 Published by Elsevier Inc.