Aim: We investigated the relationship between the severity of reciprocal ST depression and the extent of coronary artery disease in patients with inferior myocardial infarction. Method: Ninety-five consecutive patients (52 women 43 men, with a mean age of 54±5 years) who had acute inferior myocardial infarction were included in the study. Reciprocal changes in the ST segment were defined as ST depression of >1 mm in at least two out of four of the precordial leads V1–V4. All the patients had undergone coronary angiography within seven days of admission. The extension of coronary artery disease which was measured by Gensini and Reardon scores, was compared with the reciprocal changes on ECG recorded at the time of admission. Result: There was a significant correlation between reciprocal ST depression and disease extension (r=0.68 for Gensini score, r= 0.88 for Reardon score, p<0.05 for both). Conclusion: The presence of ST segment depression in the precordial leads during the acute inferior myocardial infarction was associated with greater myocardial necrosis and more frequent left coronary artery disease.