Abstract: AIM To investigate the role of necroptosis activated by RIP3-CaMKII pathway under conditions of diabetic myocardial ischemia/reperfusion. METHODS Male C57BL/6 mice (aged 3-4 months) were randomized into diabetes and normal control groups. For the diabetes group, a model of type 1 diabetes mellitus was employed. Mice were subjected to a myocardial I/R model utilizing anterior descending artery ligation for 30 minutes followed by 4-hour reperfusion. Myocardial tissue was excised after reperfusion. Western blot was used to detect RIP3 and phospho-CaMKII expression and cryosection and immunofluorescence were used to evaluate necroptosis by Evans-blue dye positive area percentage. RESULTS Compared with the normal I/R group, the diabetic I/R group showed enhanced necroptosis indicated by a higher EBD-positive area percentage (P<0.05) and increased expression of RIP3 and phospho-CaMKII (P<0.05). KN-93, an inhibitor of CaMKII, significantly reduced necroptosis in the diabetic I/R group (P<0.05). CONCLUSION Necroptosis is enhanced in diabetic myocardial I/R injury, implying that enhanced the RIP3-CaMKII pathway, which activates myocardial necroptosis, plays an important role in diabetic myocardial I/R.