The authors determined whether vasoconstriction alters the ability of a noninvasive method (Finapres®) of continuously measuring arterial blood pressure in the finger to function accurately. They compared the response of the Finapres® to blood pressures determined simultaneously by an oscillometric technique (Dinamap®) in six anesthetized patients, Vasoconstriction was detected from a photoelectric plethysmogram, which was recorded continuously from an adjacent finger. Vasoconstriction was defined as a decrease in amplitude to less than half of its highest value in one and the same patient. From the 378 paired blood pressure readings obtained in this study, 51% took place in such a vasoconstricted state. The authors found that diastolic and mean blood pressures in the finger were, on the average, 9 mmHg below those in the upper arm and that the systolic pressure was 7 mmHg above that in the upper arm. The authors concluded that the Finapres® keeps functioning well during peripheral vasoconstriction and is a recommendable method to monitor arterial blood pressure in the finger.