Objective. Aortic arch recoarctation is responsible for significant morbidity and mortality after the Norwood Stage I procedure. Cuff blood pressure (BP) gradients and echocardiographic Doppler gradients are routinely used as noninvasive screening tests for early detection, but accuracy has not been systematically tested. We sought to evaluate the ability of cuff BP and Doppler gradients, measured at routine outpatient clinic visits, to predict significant arch obstruction in single ventricle patients after the Norwood operation. Design. Consecutive patients who underwent Norwood operation at our institution were identified retrospectively. Cuff and echocardiographic gradients measured prior to the pre-Glenn catheterization were compared to peak-to-peak systolic neoaortic arch gradients obtained at catheterization. Statistical analyses, including Receiver Operator Characteristic (ROC) curves, were performed using different cutpoints for cuff and echocardiographic gradients, evaluating their ability to predict a clinically significant catheter gradient. Results. Data were obtained in 68 patients. Echocardiographic gradient cutpoints were more sensitive but less specific than cuff BP gradient cutpoints at detecting a catheter gradient ≥ 10 mm Hg. Echo gradients ≥ 20 mm Hg showed 85% sensitivity and 95% specificity in detecting a systolic catheter gradient ≥ 10 mm Hg. Conclusion. Echocardiographic Doppler outperforms cuff BP as a sensitive noninvasive screening tool for early detection of significant arch obstruction in infants after the Norwood operation.