Background: Tissue Doppler imaging (TDI) has improved the ability to detect subclinical changes in left ventricular (LV) function. The aim of this study was to investigate if asymptomatic patients with left ventricular outflow tract obstruction (LVOTO) had impaired LV systolic and diastolic function. Methods: Twenty-four asymptomatic patients with LVOTO and 26 healthy control subjects were evaluated clinically and by conventional & tissue Doppler echocardiography. TDI evaluation of longitudinal and radial tissue velocities in systole and diastole was performed. Results: lower conventional pulsed-wave Doppler peak E & A velocities of trans-mitral filling were observed in patients with LVOTO compared to controls (81± 21& 77± 31 VS 66±14 & 58± 16 cm/sec, p < 0.01). Lower longitudinal tissue velocities were found in patients compared with controls in terms of peak systolic tissue velocity, peak early diastolic tissue velocity (Em), peak late diastolic tissue velocity (Am) & peak systolic strain (4.15±1.1, 4.3± 1.6, 5.5±1.5 cm/sec & -16.5±2.3% vs. 4.9±1, 5.1±1.6, 6.3±1.4 cm/sec & -17.7±1.9 %, p < 0.05). No significant affection of radial tissue velocities was found in LVOTO patients. Conclusion: Subclinical LV systolic and diastolic dysfunction is present in our patients demonstrated only in longitudinal myocardial fibres suggesting a differential effect of LVOTO on the LV musculature or early impairment of the longitudinal myocardial fibres.