In order to assess left ventricular diastolic function in elite athletes we studied 24 athletes (mean age 21 +/- 5 years) with the echo-Doppler technique. The control group consisted of 14 healthy males (mean age 24 +/- 6 years) and 99 patients (mean age 50 +/- 14 years) with primary or secondary left ventricular hypertrophy. The following variables were calculated: age, systolic and diastolic blood pressure, septal and posterior wall thickness, left ventricular volume and dimensions, myocardial mass index and mass/volume ratio, left ventricular end-systolic and peak systolic stress, RR interval, isovolumic relaxation time (IVRT), early (E) and late (A) peak flow velocity, E/A ratio, time and rate of deceleration of early diastolic flow. Compared with the normal subjects significant differences were observed with regard to systolic blood pressure, left ventricular wall thickness, myocardial mass, mass/volume ratio and peak systolic stress in the athlete group. In spite of a noticeable increase in myocardial mass indexes, all the diastolic function parameters were normal in the athletes. In this group a linear positive correlation between rapid filling indexes, ventricular mass and mass/volume ratio exists. These correlations are not present in the patients group. Moreover a linear negative correlation between RR interval and late diastolic flow velocity was found. In conclusion, the global diastolic ventricular function, evaluated with the echo-Doppler technique, is normal in athletes in spite of an increase in ventricular mass. Th early diastolic flow velocity is in direct proportion with mass increase and may represent one of the physiological mechanisms of the athlete heart adaptations.