1. The disappearance rate of intravenously injected Evans Blue, plasma volume, cardiac output, and blood pressure were measured in seven normotensive and eighteen hypertensive subjects.
2. Plasma volume was found to be negatively correlated with the mean arterial pressure, Evans Blue disappearance rate and packed cell volume.
3. Faster disappearance rate of Evans Blue in hypertensive subjects may be due to an abnormality of mixing of the label or of the capillaries.