Sweating and vasodilatation in the cutaneous circulation were investigated during passive body heating in eight borderline hypertensive subjects and in eight normotensive controls, matched for age, sex and body mass. Blood flow through the finger and forearm was examined in relation to changes in oral temperature; blood pressure, heart rate and sweating in the forehead and forearm were also measured. Systolic blood pressure decreased in borderline hypertensive subjects during the early stages of heating and then returned to baseline, but increased in normotensives. Increases in skin blood flow and decreases in cutaneous vascular resistance were similar in both groups. Thus, cutaneous vasodilatation during moderate body heating did not differ between normotensive subjects and subjects with mildly elevated blood pressure. These findings do not rule out attenuation of cutaneous vasodilatation in mildly hypertensive subjects during more intense heating.