The American Academy of Pediatrics recently published evidence-based guidelines for a standardized approach to pulse oximetry as a screening tool for critical congenital heart disease (CCHD). The addition of CCHD screening to the standard newborn examination may lead to earlier detection of CCHD and subsequently decreased morbidity and mortality. We report a case of CCHD with excessive pulmonary blood flow that went undetected during routine newborn screening. Healthcare practitioners and families need to be aware of the limitations of CCHD screening.