Objective: In a subgroup of patients with inferior myocardial infarction (MI), both the right coronary artery (RCA) and circumflex coronary artery(Cx) show potentially culprit lesions, and angiography may be insufficient to determine which artery is responsible for the clinical presentation.Although many electrocardiographic (ECG) algorithms have been proposed for identifying the infarct-related artery in patients with inferior MI,it is unclear whether the current algorithms have the discriminative power to identify the real culprit artery in these patients.Methods: The patients with the diagnosis of acute inferior MI and underwent coronary angiography were enrolled in the study. The prediction ofthe infarct-related artery was attempted from the admission ECG using published algorithms and criteria. For the angiographic definition of theinfarct-related artery, multiple criteria were used.Results: Total 417 inferior MI cases were enrolled during the study period; the final patient population comprised of 318 patients. Forty-five patients (14.2%) had both RCA and Cx lesions on coronary angiography. Although several criteria and algorithms are able to identify the infarct-related artery in the general inferior MI population, they lose their strength in patients with both RCA and Cx lesions. Only the Aslanger-Bozbeyoğlucriterion emerges as a more powerful diagnostic test with a sensitivity, specificity, and c-statistic of 80%, 48%, and 0.650, respectively for thewhole population (p<0.001) and 81%, 58%, and 0.709, respectively, for patients with both RCA and Cx lesions (p=0.019).Conclusion: The Aslanger-Bozbeyoğlu criterion is not only helpful in differentiating the infarct territory in combined inferior and anterior STsegment elevation as previously shown, but also valuable in identifying the infarct-related artery in patients with inferior STEMI with criticallesions in both the RCA and the Cx. (Anatol J Cardiol 2020; 23: 318-23)