Infants with persistent conjugated jaundice, lasting longer than 14 days of age in a term infant and 21 days in a preterm infant, should be referred to a national paediatric liver unit for investigation of the cause. This paper reviews the ultrasound findings in such cases with a particular emphasis upon the diagnosis of biliary atresia. Infants with persistent conjugated jaundice, lasting longer than 14 days of age in a term infant and 21 days in a preterm infant, should be referred to a national paediatric liver unit for investigation of the cause. This paper reviews the ultrasound findings in such cases with a particular emphasis upon the diagnosis of biliary atresia.