Background: Ischemic mitral regurgitation (MR) is considered a prognostic factor of heart failure after myocardial infarction (MI). Many cases, ischemic MR was improved by appropriate medical and interventional treatment. Some cases still remained or aggravated until several months. The objective of the present study was to find the associated factors of remained ischemic MR in patients with acute MI. Methods: A total of 611 consecutive patients (62.4짹12 years, 361 males) with acute MI who examined by echocardiography at admission and after six month were divided into two groups according to the extent of ischemic MR; group I associated with remained or aggravated MR (n= 281, 63.6 짹 11 years, 193males) vs. group II associated with improved or absent MR (n=329, 62.1 짹 12 years, 243 males). Various clinical, laboratory, echocardiographic parameters and coronary angiographic findings were compared between two groups. Results: Body weight, body mass index, abdominal and hip circumference, systolic and diastolic blood pressure were lower in group I than group II (p<0.05). Diabetes and ST-segment elevation, multi-vessel involving and in-hospital complication were more frequently found in group I than in group II significantly (p<0.05). The levels of B-type nitriuretic peptide was significantly increased in group I than in group II (p<0.001). Left ventricular ejection fraction was lower, left venticlular filling pressure (e/e���) was higher in group I than in group II (p<0.001). By multivariate analysis, low body mass index less than 24 (odds ratio 1.68, confidence interval 1.134-2.489, P=0.01) and diabetes (odds ratio 1.57, confidence interval 1.013-2.499, P<0.05) were independently affects remained MR. One-year major adverse cardiac event including death were developed in group I and goup II. Conclusions: Low body mass index and diabetes independently associated with remained Ischemic MR in patients with acute MI.