1. In hypertensive patients the general pattern of spontaneously occurring sympathetic activity (SA) as well as the sympathetic responses to various manoeuvres are similar to those of the normotensive controls.
2. This suggests that the multi-unit SA recorded in muscle and skin nerves of hypertensive patients are made up of impulses from the same fibre populations as in normotensive subjects and that the outflow of these impulses is controlled by similar mechanisms in the two groups.
3. More quantitative evidence obtained under standardized external conditions is necessary before it can be decided whether there is an increased strength of the sympathetic outflow to the skin in hypertensive patients.