To evaluate the changes of left ventricular diastolic and systolic function and the timing of these changes in the early stages of acute myocardial infarction, serial echocardiograms were performed in 10 male patients (mean age of 56 years) with acute myocardial infarction, undergoing reperfusion by thrombolysis (recombinant tissue plasminogen activator). Echocardiograms were performed before reperfusion and 3, 6, 12, 24, 48, 72 hours, 7 and 14 days after thrombolysis. Significant differences of heart rate, systolic and diastolic blood pressure, left ventricular end diastolic volume, end-systolic volume and ejection fraction were not found. The mean regional wall motion index improved from 1.02 +/- 0.50 to 0.89 +/- 0.51 (p less than 0.05) at 48 hours; to 0.79 +/- 0.46 (p less than 0.01) at 72 hours; to 0.69 +/- 0.43 (p less than 0.001) at 7 days and to 0.61 +/- 0.40 at 14 days (p less than 0.001). The deceleration time decreased from 223 +/- 33 to 169 +/- 30 ms (p less than 0.001) 24 hours after reperfusion without further improvement. E peak velocity and E/A ratio significantly increased at 72 hours, while A peak velocity was not statistically different. A slow and progressive recovery of left ventricular function occurred after thrombolysis in acute myocardial infarction. Left ventricular diastole improves earlier while regional systolic function improves slowly till the hospital discharge.