Mitochondrial uncoupling proteins, which secure physiological uncoupling of oxidative phosphorylation, have been proposed to serve as an oxidative-stress compensatory mechanism. Here, heart-derived H9c2 cells acquired improved resistance to injury upon transfection of the prototypic uncoupling protein UCP1. Following hypoxia/reoxygenation, stable overexpression of UCP1 provided enhanced cardioblast survival with preserved mitochondrial structure and function, while limiting reactive oxygen species formation. Thus, transfection of mitochondrial UCP1 provides a strategy for generation of a stress-resistant cardiac cell phenotype.