OBJECTIVE. The goal was to determine the cost-effectiveness of ambulatory blood pressure monitoring in the initial evaluation of stage 1 hypertension. METHODS. Retrospective chart review of data for children referred to Texas Children's Hospital hypertension clinic between January 2005 and August 2006 was performed. We compared the costs of standard evaluations versus the initial use of ambulatory blood pressure monitoring for children with clinic blood pressure measurements suggesting stage 1 hypertension. Charges for clinic visits, laboratory tests, and imaging were obtained from the Texas Children's Hospital billing department. RESULTS. A total of 267 children were referred. One hundred thirty-nine children did not receive ambulatory blood pressure monitoring;54 met clinical indications for ambulatory blood pressure monitoring but did not receive it because it was not a covered expense (44 children) or the family refused the study (10 children). One hundred twenty-six children received clinically indicated ambulatory blood pressure monitoring, paid for either through insurance or by the family. Fifty-eight children (46%) had confirmed white-coat hypertension, 62 (49%) stage 1 hypertension, and 6 (5%) stage 2 hypertension. With the observed prevalence of white-coat hypertension, initial ambulatory blood pressure monitoring use yielded net savings after evaluation of 3 patients, with projected savings of $2.4 million per 1000 patients. CONCLUSIONS. Ambulatory blood pressure monitoring in the initial evaluation of suspected childhood hypertension is highly cost-effective. Awareness of cost saving potential may increase the availability of ambulatory blood pressure monitoring for evaluation of new-onset hypertension. Copyright © 2008 by the American Academy of Pediatrics.