Whether the decrease in large artery compliance, observed in hypertensive patients (HT), is due to an increase in distending pressure or to intrinsic alterations of the vascular wall remains much debated. We determined the diameter-pressure curve of the common carotid artery over the systolic-diastolic range, then derived the compliance-pressure curve, in order to compare arterial compliance in normotensive subject (NT) and in HT, for a common level of distending blood pressure: 100 mmHg (isobaric compliance). Fourteen NT and 15 never treated essential HT were included in the study. The diameter-pressure curve of the common carotid artery was determined non-invasively by simultaneously and continuously recording the systolic-diastolic changes in internal diameter (using a high resolution echotracking system) and pressure waveform (using high fidelity applanation tonometry on the contralateral artery) over 4-6 cardiac cycles. The level of MAP of the carotid pressure waveform was determined electronically and set equal to mean brachial pressure. Compliance-pressure curve was then derived from the pressure-diameter curve in order to determine compliance (C) for any given level of blood pressure, particularly MAP (CMAP) and 100 mmHg (C100). Despite the considerable differences in blood pressure, the compliance-pressure curve of HT was not different from that of NT. CMAP decreased with aging (p < 0.001) and MAP (p < 0.001). According to age, CMAP was reduced in HT as compared to NT (84 +/- 49 vs 116 +/- 52 mm2.mmHg.10(-3) p < 0.01). C100 decreased with aging (p < 0.05) but not with MAP. According to age, C100 was not reduced in hypertensives.(ABSTRACT TRUNCATED AT 250 WORDS)