The Vasotrac is a device that provides near-continuous and noninvasive arterial blood pressure monitoring and may be an alternative to direct intraarterial measurement. It has been evaluated in adult patients, but minimal information is available for pediatric patients. We evaluated agreement between measurements of arterial blood pressure and heart rate obtained from the Vasotrac versus an arterial catheter in a pediatric population. Children undergoing corrective cardiac surgery were enrolled. Simultaneous arterial blood pressure measurements were obtained postoperatively from the Vasotrac unit and an arterial catheter. Bland-Altman plots were constructed to assess agreement. Paired correlation analysis, bias, and precision calculations were performed. Sixteen patients, mean age 10.1 +/- 2.3 yr and weight 34.6 +/- 11.9 kg, were enrolled. Four-thousand-one- hundred- two paired measurements were obtained. Arterial blood pressures measured noninvasively correlated with catheter measurements with Pearson r values of 0.90, 0.80, and 0.91 for systolic, diastolic, and mean arterial blood pressures, respectively (all P < 0.001). There was excellent agreement between arterial blood pressure measurement methods. Absolute mean differences based on mixed-model regression with 95% confidence intervals were 4.0 mm Hg (3.0-5.0 mm Hg), 4.3 mm Hg (3.1-5.5 mm Hg), and 3.5 mm Hg (2.5-4.0 mm Hg) for systolic blood pressure, diastolic blood pressure, and mean blood pressure, respectively. Arterial blood pressure measurements obtained from the Vasotrac agreed well with invasive arterial monitoring in pediatric patients.