It is demonstrated that Essential Hypertension is accompanied by a reduction of large artery distensibility (Dist), which represents a marker of demonstrated prognostic significance. Dist can be assessed by echotracking derived systo-diastolic changes in aortic diameter versus blood pressure changes. However, a less operator dependent and more precise assessment might be obtained by nuclear magnetic resonance (NMR). This study was done to compare aortic (Ao) Dist obtained by echotracking and NMR in normotensive and hypertensive patients. We studied 14 treated essential hypertensives (age 36 ± 3.5 years, blood pressure 126 ± 3/78 ± 1.7 mmHg means ± SE) and 15 matched normotensives controls (blood pressure 116 ± 3.0/73 ± 2.4 mmHg). Systodiastolic changes in thoracic (T, 1 cm above the celiac tripode) and abdominal (A, 1 cm above bifurcation) Ao were obtained by either method. Dist was calculated via the Reneman formula using tonometric carotid pulse pressure. NMR Dist values were systematically greater than the echotracking one (Hypertensives T 7.2 ± 0.5 vs 3.0 ± 0.5, A 6.0 ± 0.5 vs 2.9 ± 0.4 1/mmHg 10⁻¹, Normotensives, T, 8.6 ± 0.5 vs5.2 ± 0.5, A 7.5 ± 0.5 vs3.6 ± 0.3 1/mmHg 10⁻¹ p<0.05). The correlation between RMN and echotracking obtaind values was significant. Dist was systematically and significantly lower in H than N (p always <0.05) . No significant differences were observed between NMR T and A aAo arterial diameter. Thus, Ao Dist may be underestimated by echotracking method. Data obtained by the two approaches are similarly capable of detecting Dist reduction in hypertension. This scores in favour of continuing use of the much low expensive echotracking method.