Background: Left atrial (LA) remodeling as well as left ventricular(LV) remodeling has been studied as an important predictor of survival after acute myocardial infarction while the TIMI myocardial perfusion(TMP) grade has been considered as an useful angiographic marker to assess the efficacy of myocardial reperfusion. We postulated that the TMP grade after primary angioplasty might affect the LA remodeling in patients with acute myocardial infarction (AMI). Methods: Thirty patients (55짹12 years old, 24 males) with anterior and inferior AMI were enrolled. The TMP was graded by two experienced experts after successful primary angioplasty such as 0-no myocardial blush; 1-minimal myocardial blush; 2-moderate myocardial blush; 3-normal myocardial blush. Thirteen patients had TMP grade 0 and 1; 8 with TMP grade 2; 9 with TMP grade 3. We performed a 2-D transthoracic echocardiogram with assessment of LV systolic and diastolic function including measurement of LA volume within 24 hours after primary angioplasty and after 6 months. Results: The LA volume was significantly increased in patients with TMP grade 0 and 1 than in patients with TMP grade 3 and with TMP grade 2 (Table1). On the other hand, patients with TMP grade 0 and 1 had a trend toward higher LV volume change than in patients with TMP grade 2 and with TMP grade 3, but that was not significant. Conclusion : These findings suggest that LA remodeling might be affected by myocardial reperfusion after primary angioplasty in AMI. The TMP grade might be one of indicators to predict LA remodeling.