To assess the left ventricular regional relaxation abnormalities in patients with hypertrophic cardiomyopathy (HCM) by quantitative tissue velocity imaging (QTVI), Doppler echocardiography and QTVI were performed in HCM (n=10) and healthy subjects (n=11) at apical longaxis, two-chamber and four-chamber views. Regional early diastolic velocity (rVe) and regional atrial contraction (rVa) were measured at each segment of ventricular middle, basal and annular levels. Mean rVe and mean rVa at three levels as well as mean rVe/rVa ratio were calculated. Our results showed that transmitral inflow peak velocities during early diastole (E) and atrial contraction (A) were also measured and E/A ratio was calculated. The rVe of all left ventricular segments in HCM were lower than those in healthy subjects (P＜0.05), but compared with healthy subjects majority of rVa in HCM were not different except inferior wall and anterior wall. E between HCM and healthy subjects was different (P= 0. 036), while mean rVe between them was significantly different (P＜0. 0001). Mean rVa and mean rVe/rVa of three levels were lower in HCM than in healthy subjects (P＜0.05), but there were no differences in A and E/A between them (P=0.22,P= 0. 101). Left ventricular regional myocardial relaxation is reduced in HCM. Transmitral inflow E and A are influenced by preload, relaxation of myocardium and atrial contraction, etc. , while rVe and rVa reflect myocardial relaxation function independently. QTVI is more sensitive and more accurate than conventional Doppler imaging for characterizingregional diastolic properties in HCM.