1. Mean supine plasma noradrenaline was lower in 12 male laboratory staff (0·24 ± 0·02 μg/l) than similarly normotensive out-patients (0·44 ± 0·07 μg/l).
2. In 164 non-medical hospital staff, plasma noradrenaline increased with age in white males only.
3. Plasma noradrenaline was significantly higher in women than men.
4. There was no relationship between supine blood pressure and plasma noradrenaline in normotensive or hypertensive subjects.