['To investigate whether preconditioning with high mobility group box 1 protein (HMGB1) could reduce myocardial ischemia-reperfusion (I/R) injury.', 'Infarct size, lactate dehydrogenase (LDH), creatine kinase (CK), tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) were assessed. HMGB1 preconditioning reduced significantly the infarct size induced by I/R. The LDH, CK, TNF-α and IL-6 levels were significantly decreased by HMGB1 preconditioning compared to those in the I/R group.'] Does preconditioning with high mobility group box 1 protein protect against myocardial ischemia-reperfusion injury?