BACKGROUND Myocardial ischemia-reperfusion injury (IRI) is an important injury mechanism of myocardial infarction. The purpose of this study was to explore the effects of L-carnitine (LC) on myocardial IRI and its mechanism. MATERIAL AND METHODS The IRI model was made by ligating the left anterior descending coronary artery. Then, we injected LC intraperitoneally into the rats of the experimental group to assess the effect of LC on IRI rats by use of serum markers, Western blot, and qRT-PCR. H9c2 cells were cultured and then treated with hypoxia-reoxygenation. The effect of LC on oxidative stress, apoptosis, and nuclear transcription-related factor 2/heme oxygenase-1 (Nrf2/HO-1) signaling pathway of H9c2 cells were detected by Western blot, RT-PCR, and flow cytometry. RESULTS LC significantly reduced malondialdehyde (MDA), creatine kinase (CK), and lactate dehydrogenase (LDH) levels in rat myocardial tissue and increased superoxide dismutase (SOD) expression. LC also increased the expression of SOD1/2 and Bcl-2 in rat myocardial tissue and H9c2 cells and decreased the expression of caspase3/8 and Bax. In addition, LC increased the expression of Nrf2/HO-1 signaling pathway-related molecules in H9c2 cells and increased the activity of the Nrf2/HO-1 signaling pathway. Moreover, inhibition of the Nrf2/HO-1 signaling pathway attenuated the protective effect of LC on H9c2 cells. CONCLUSIONS LC can activate the Nrf2/HO-1 signaling pathway and reduce oxidative stress and apoptosis in cardiomyocytes, thereby reducing myocardial IRI.