Objective:  The objectives of the study were to assess myocardial systolic and diastolic functions by myocardial performance index (MPI) and its relationship with E – wave deceleration time (DT) in early phase of acute Q-wave myocardial infarction (MI). Materials and Methods:  We performed nongeometric Doppler-derived echocardiography to assess combined systolic and diastolic functions using myocardial performance index in 50 patients with acute Q-wave MI at early phase of events, (25 pts with anterior MI and 25 pts with inferior MI). The index is defined as the sum of the isovolumic contraction and isovolumic relaxation times divided by ventricular ejection time and was obtained by Doppler measurement from the diastolic mitral inflow and left ventricular outflow velocity-time intervals. Results:  As a result, the index was 0.54±0.1 in all patients with MI. We also estimated the higher MPI and DT values in anterior than inferior MI (MPI: 0.61±0.07 vs., 0.46±0.06, p<0.001; DT: 244±64 msec vs. 204±31.2 msec, p=0.005, respectively). Myocardial performance index was positively correlated with DT in inferior MI (r=0.42, p<0.035) and negatively correlated with anterior Mİ (r=- 0.72, p=0.0001). Conclusion:  These data suggest that Doppler-derived MPI reflects severity of global left ventricular dysfunction in early phase of acute MI and may be a useful parameter in these patients.