The pulse-wave velocity along the brachial radial artery was measured in 38 subjects and volume distensibility values were calculated. 2. Measurements made at each subject's resting blood pressure showed that those with high blood pressure had higher pulse-wave velocity values and hence less distensible arteries. 3. An acute rise in arterial distending pressure was accompanied by a rise in pulse-wave velocity. 4. When pulse-wave velocity was remeasured in all subjects at identical arterial distengin pressures, no difference was found between hypertensive and normal subjects. 5. It appears that poor distensibility of large arteries in hypertensive subjects is a consequence of the elevated distending pressures and not due to irreversible structural changes in the arterial wall.
