A retrospective study of 17 babies admitted to the neonatal intensive care unit of the Royal Maternity Hospital, Belfast, was undertaken to determine the causes and prognosis of conjugated hyperbilirubinaemia (direct fraction greater than 20% of total) over a five year period. Mean gestational age was 29 weeks and mean birth weight was 1,240g with a 2:1 male preponderance. All babies had a complicated clinical course involving prolonged periods of parenteral nutrition and many episodes of sepsis. Liver damage was not found to be a contributory factor to death in any baby who died before the age of one year. Bilirubin levels in the survivors had returned to normal within one year. No permanent pathological cause of cholestasis, such as biliary atresia, was ascribable to any of the cases, indicating that extensive investigation to exclude anatomical causes in this population is unlikely to prove rewarding.