In almost 200 case of left ventricular hypertrophy (LVH) secondary to hypertension (HT), including 75 cases with conduction disorders, 100 cases of normal adults and 20 cases of normal children, segmental (initial horizontal vector, maximal anterior and posterior vector of the QRS) and spatial vectorial parameters were correlated to segmental echocardiographic parameters (septum, anterior and posterior wall of the left ventricle) and mass parameters (left ventricular mass index). The only significant quantitative variables in hypertensive LVH are: on electrocardiography: the AQRS and Sokolow's index: on vectocardiography: the spatial vector: its magnitude, azimuth and elevation, the maximal posterior vector: its amplitude, the maximal anterior vector: its amplitude, the maximal width of the QRS azimuth of the efferent limb of the QRS, the ventricular gradient in the horizontal, frontal and sagittal planes; on echocardiography: the left ventricular mass index, the diastolic thickness of the septum and the VMNES, the diastolic thickness of the posterior wall of the left ventricle and its percentage thickening. The only significant correlations were observed between: the maximal posterior vector of QRS and the diastolic thickness of the posterior wall of the left ventricle: 0.01 < alpha < 0.02; the spatial vector and the left ventricular mass index: 0.01 < alpha < 0.001. The presence of a conduction disorder does not modify these last two qualitative variables but alters their correlation.