Racial differences in left ventricular (LV) structure are suggested by clinical and experimental studies. This study evaluates if racial differences in LV performance exist comparing black to white young males, by tissue Doppler echocardiography and myocardial performance index (MPI). We examined 40 healthy males, 20 blacks (mean age 27.6 +/- 4.4 years) and 20 whites (mean age 26.5 +/- 6.7 years). All subjects underwent conventional echocardiography, tissue Doppler echocardiography, and MPI assessment. No differences were found in LV diameters, volumes, mass, and hemodynamic measurements. Septal and posterior wall thicknesses were significantly increased in black subjects as well as the relative wall thickness. Systolic and diastolic functions estimated by conventional parameters were superimposable in the two groups. In black subjects, a significant increase of septal S-wave, peak velocity, and time-velocity integral were found. MPI was significantly higher in black compared to white subjects (0.46 +/- 0.05 vs 0.40 +/- 0.06, P < 0.002). A significant correlation between MPI and relative wall thickness (r = 0.54) was demonstrated. Besides, MPI correlated with S(pv) (r = 0.55) and S(tvi) (r = 0.38) at the septal site. In conclusion our data show a higher MPI in black subjects that seems to be geometry-dependent. Correlations between MPI and tissue Doppler echocardiography systolic indexes were found. Our findings suggest that racial differences in LV performance exist, especially, in the systolic function, even in the absence of other conventional echocardiographic changes.