To assess the presence of subclinical left ventricular myocardial dysfunction in subjects with high-normal blood pressure (BP) and untreated arterial hypertension, using three-dimensional (3D) echocardiography strain analysis. This cross-sectional study included 49 subjects with optimal BP, 50 subjects with high-normal BP, and 50 newly diagnosed untreated hypertensive patients matched by gender and age. All the subjects underwent 24 h blood pressure monitoring and complete two-dimensional and 3D echocardiography examination. The enrolled subjects were grouped according to 24 h systolic BP values, dividing the subjects with optimal BP from those with high-normal BP and the hypertensive patients (cut-off values were 120 and 130 mmHg, respectively). 3D global longitudinal strain was significantly lower in the high-normal BP group and the hypertensive patients, in comparison with the optimal BP group (−20.5 ± 3.3 vs. −18.7 ± 2.8 vs. −17.6 ± 2.7 %, p < 0.001). Similar results were obtained for 3D global circumferential strain (−18.6 ± 3 vs. −17.1 ± 2.9 vs. −16 ± 2.5 %, p < 0.001), as well for 3D global radial strain (49.4 ± 9.5 vs. 44.7 ± 8.1 vs. 43.5 ± 7.8 %, p = 0.002), and global area strain (−31.2 ± 4.8 vs. −28.7 ± 4.2 vs. −27.1 ± 4.5 %, p < 0.001). LV twist was increased in the hypertensive patients in comparison with the high-normal and the optimal BP groups (10.1° ± 2.4° vs. 10.8° ± 2.6° vs. 13.8° ± 3.1°, p < 0.01), whereas untwisting rate significantly and gradually decreased from the optimal BP group, across the high-normal BP group, to the hypertensive patients (−135 ± 35 vs. −118 ± 31 vs. −102 ± 27°/s, p < 0.001). 3D echocardiography revealed that the subjects with high-normal BP suffered subclinical impairment of LV mechanics similar as the hypertensive patients.