I have reviewed clinical trials that provide data relative to the comparative rates, means, or odds ratio of jaundiced normal breast-fed newborns vs jaundiced normal formula-fed newborns. A pooled analysis of 12 studies revealed moderate jaundice (serum bilirubin level, greater than or equal to 12 mg/dL) in 514 of 3,997 breast-fed vs 172 of 4,255 formula-fed newborns. An analysis of six of these 12 studies demonstrated severe jaundice (serum bilirubin level, greater than or equal to 15 mg/dL) in 54 of 2,655 breast-fed vs ten of 3,002 formula-fed newborns. Eleven of 13 studies found breast-fed newborns to have a higher mean serum bilirubin level. One study of 12,023 newborns found a significant (odds ratio, 1.80) relationship between breast-feeding and jaundice of the newborn. In conclusion, breast-feeding is one common cause of jaundice in normal newborns in the first week of life and beyond.