The standard for ambulatory arrhythmia detection in children is the Holter monitor. The Zio XT (Zio) patch has been FDA-approved for use in adults. However, its utility in children has not been directly compared with the Holter. We studied the ability to detect arrhythmias and patient comfort of the Zio versus the Holter in children. Patients <22 years old were prospectively enrolled to wear the Holter and Zio simultaneously for 48 hours at our institution. Detection of clinically significant arrhythmias was compared using McNemar's test. Wear-time and artifact time was compared using Wilcoxon sign test. Patient satisfaction ratings were analyzed with paired t tests. Two hundred patients (57% male) were included for analysis. The median age was 13.5 years (range 23 days to 21.7 years), and 40% had heart disease. The Zio and Holter had comparable median wear-times, 48.2 hours (interquartile range [IQR] 45.8 to 50.2]) versus 48.0 (48.0 to 48.0), respectively, p = 0.14, but the Zio had less artifact than the Holter, 2.8% (IQR 1.1 to 8.6) versus 5.6% (2.4 to 15.7), respectively, p <0.001. There was no difference in detection of clinically significant arrhythmias for the Zio versus the Holter (p = 0.23), however 75% of patients preferred the Zio over the Holter (p <0.001) due to lack of wires and the ability to shower. In conclusion, the Zio patch is as good as the Holter monitor in detection of clinically significant arrhythmias in children with less artifact. Patients/parents more often preferred the Zio over the Holter.