A study on the effects of a popular Chinese herb commonly given to newborn infants was undertaken. ‘Chuen-Lin’, Coptis chinensus/japonicum, which is consumed by 28–51% of Chinese infants, was found to have a significant effect in displacing bilirubin from its serum protein binding as assessed by the peroxidase oxidation method. Taking this herbal tea may thus increase the risk of brain damage by free bilirubin in jaundiced infants. As neonatal hyperbilirubinaemia is highly prevalent among Southern Chinese, the use of Chuen-Lin in the perinatal period must be strongly discouraged.