We studied in children and adolescents the performance of two devices for blood pressure measurements at the wrist: "Blood pressure watch" (BPW) and Omron R1 (OR1). They were tested against auscultatory blood pressure readings at the upper arm. Wrist circumference correlated to the aged was greater than 13.5 cm in nearby all subjects older than 12 years. BPW overestimated systolic blood pressure for more than 10 mm Hg and diastolic blood pressure for 4 to 7 mm Hg in all subjects. OR1 underestimated both systolic and diastolic blood pressure by 5 to 6 mm Hg in the group with a wrist greater than 13.5 cm and by 8 to 9 mm Hg in the group with a smaller wrist. No difference was found between left and right wrists by OR1.