The Finapres methodology offers continuous measurement of blood pressure (BP) in a noninvasive manner. The latest development using this methodology is the Nexfin monitor. The present study evaluated the accuracy of Nexfin noninvasive arterial pressure (NAP) compared with auscultatory BP measurements (Riva-Rocci/Korotkoff, RRK). In supine subjects NAP was compared to RRK, performed by two observers using an electronic stethoscope with double earpieces. Per subject, three NAP-RRK differences were determined for systolic and diastolic BP, and bias and precision of differences were expressed as median (25th, 75th percentiles). Within-subject precision was defined as the (25th, 75th percentiles) after removing the average individual difference. A total of 312 data sets of NAP and RRK for systolic and diastolic BP from 104 subjects (aged 18-95 years, 54 males) were compared. RRK systolic BP was 129 (115, 150), and diastolic BP was 80 (72, 89), NAP-RRK differences were 5.4 (-1.7, 11.0) mm Hg and -2.5 (-7.6, 2.3) mm Hg for systolic and diastolic BP, respectively; within-subject precisions were (-2.2, 2.3) and (-1.6, 1.5) mm Hg, respectively. Nexfin provides accurate measurement of BP with good within-subject precision when compared to RRK.