Approximately half of all newborns with congenital heart disease are asymptomatic in the first few days of life. Early detection of ductal-dependant cardiac malformations prior to ductal closure is, however, of significant clinical importance, as the treatment outcome is related to the time of diagnosis. Pulse oximetry has been proposed for early detection of congenital heart disease. The aims of the present study were: 1) to determine the effectiveness of a pulse-oximetric screening performed on the first day of life for the detection of congenital heart disease in otherwise healthy newborns and 2) to determine if a pulse-oximetric screening combined with clinical examination is superior in the diagnosis of congenital heart disease to clinical examination alone. This is a prospective, multi-centre study. Postductal pulse oximetry was performed between six and twelve hours of age in all newborns of greater than 35 weeks gestation. If pulse-oximetry-measured arterial oxygen saturation was less than 95%, echocardiography was performed. Pulse oximetry was performed in 3,262 newborns. Twenty-four infants (0.7%) had repeated saturations of less than 95%. Of these infants, 17 had congenital heart disease and five of the remaining seven had persistent pulmonary hypertension. No infant with a ductal-dependant or cyanotic congenital heart disease exhibited saturation values greater or equal to 95%. Conclusion: postductal pulse-oximetric screening in the first few days of life is an effective means for detecting cyanotic congenital heart disease in otherwise healthy newborn