Background: Our goal in this study was to examine the changes in the left atrial functions over a period of 3 months by using left atrial volume measurements in patients with anterior myocardial infarction (MI). Methods and Results: Seventy-three patients with anterior MI who consulted our hospital in the first 12 hours starting from the onset of the chest pain and who exhibited ST elevation were enrolled in the study. The left atrial functions of the patients were evaluated by transthoracic echocardiography for a total number of four times; first at the time of the visit to the hospital, then in the first week, and then in the first and third months. Eight (10.95%) of the 73 patients included in the study died during the follow-up. The remaining 65 patients completed the 3-month study period. Of these 65 patients, primary percutaneous transluminal coronary angioplasty (PTCA) was performed for 24 (36.9%) patients and thrombolytic therapy was given to 13 (20%), whereas 28 (43.1%) patients were given only medical treatment. Left atrium (LA) maximum transverse diameter, LA maximum, minimum, and presystolic volume, LA active emptying volume and fraction were found to increase significantly in comparison to baseline detected for this parameter in the first and third months (P < 0.001). However, LA passive emptying volume and fraction was found to decrease significantly in comparison to baseline detected for this parameter in the first and third months (P < 0.001). Conclusions: An increase in the diameter, volume, and dimensions of LA during atrial remodeling was detected. LA passive emptying fraction was found to decrease, whereas atrial active emptying function was found to increase to compensate for this change.